--- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '21274' abstract: - lang: eng text: "Many white dwarfs are observed in compact double white dwarf binaries, and through the emission of gravitational waves, a large fraction are destined to merge. The merger remnants that do not explode in a Type Ia supernova are expected to initially be rapidly rotating and highly magnetized. In this work, we present our discovery of the variable white dwarf ZTF J200832.79+444939.67, hereafter ZTF J2008+4449, as a likely merger remnant showing signs of circumstellar material without a stellar or substellar companion. The nature of ZTF J2008+4449 as a merger remnant is supported by its physical properties: it is hot (35 500 ± 300 K) and massive (1.12 ± 0.03 M\r\n ⊙\r\n ), rapidly rotating with a period of ≈6.6 minutes, and likely possesses exceptionally strong magnetic fields (∼400−600 MG) at its surface. Remarkably, we detect a significant period derivative of (1.80 ± 0.09)×10\r\n −12\r\n \ s/s, indicating that the white dwarf is spinning down, and a soft X-ray emission that is inconsistent with photospheric emission. As the presence of a mass-transferring stellar or brown dwarf companion is excluded by infrared photometry, the detected spin-down and X-ray emission could be tell-tale signs of a magnetically driven wind or of interaction with circumstellar material, possibly originating from the fallback of gravitationally bound merger ejecta or from the tidal disruption of a planetary object. We also detect Balmer emission, which requires the presence of ionized hydrogen in the vicinity of the white dwarf, showing Doppler shifts as high as ≈2000 km s\r\n −1\r\n \ . The unusual variability of the Balmer emission on the spin period of the white dwarf is consistent with the trapping of a half ring of ionized gas in the magnetosphere of the white dwarf.\r\n " acknowledgement: "We thank Lynne Hillenbrand and Soumyadeep Bhattacharjee for helpful discussions, and Kishalay De for his help with the WIRC\r\nreduction pipeline. IC was supported by NASA through grants from the Space\r\nTelescope Science Institute, under NASA contracts NASA.22K1813, NAS5-\r\n26555 and NAS5-03127. TC was supported by NASA through the NASA Hubble\r\nFellowship grant HST-HF2-51527.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research\r\nin Astronomy, Inc., for NASA, under contract NAS5-26555. This project has\r\nreceived funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 101020057). This work was based on observations obtained with the\r\nSamuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar\r\nObservatory as part of the Zwicky Transient Facility project. ZTF is supported\r\nby the National Science Foundation under Grants No. AST-1440341, AST2034437, and currently Award #2407588. ZTF receives additional funding from\r\nthe ZTF partnership. Current members include Caltech, USA; Caltech/IPAC,\r\nUSA; University of Maryland, USA; University of California, Berkeley, USA;\r\nUniversity of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel\r\nUniversity, USA; University of North Carolina at Chapel Hill, USA; Institute\r\nof Science and Technology, Austria; National Central University, Taiwan, and\r\nOKC, University of Stockholm, Sweden. Operations are conducted by Caltech’s\r\nOptical Observatory (COO), Caltech/IPAC, and the University of Washington at\r\nSeattle, USA. This work has made use of data from the European Space Agency\r\n(ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by\r\nthe Gaia Data Processing and Analysis Consortium (DPAC, https://www.\r\ncosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Pan-STARRS1 Surveys (PS1)\r\nand the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the PanSTARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck\r\nInstitute for Extraterrestrial Physics, Garching, The Johns Hopkins University,\r\nDurham University, the University of Edinburgh, the Queen’s University Belfast,\r\nthe Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through\r\nthe Planetary Science Division of the NASA Science Mission Directorate, the\r\nNational Science Foundation Grant No. AST–1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory,\r\nand the Gordon and Betty Moore Foundation. This work made use of Astropy\r\n(http://www.astropy.org): a community-developed core Python package\r\nand an ecosystem of tools and resources for astronomy (Astropy Collaboration\r\n2013, 2018, 2022)." article_number: A188 article_processing_charge: Yes article_type: original author: - first_name: Andrei-Alexandru full_name: Cristea, Andrei-Alexandru id: 4d500bea-31f8-11ee-a48d-d4904fb363c7 last_name: Cristea - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Tim full_name: Cunningham, Tim last_name: Cunningham - first_name: John C. full_name: Raymond, John C. last_name: Raymond - first_name: Stephane full_name: Vennes, Stephane last_name: Vennes - first_name: Adela full_name: Kawka, Adela last_name: Kawka - first_name: Aayush A full_name: Desai, Aayush A id: 502cfd30-32c1-11ee-a9a4-d8dad5c6739e last_name: Desai - first_name: David R. full_name: Miller, David R. last_name: Miller - first_name: J. J. full_name: Hermes, J. J. last_name: Hermes - first_name: Jim full_name: Fuller, Jim last_name: Fuller - first_name: Jeremy full_name: Heyl, Jeremy last_name: Heyl - first_name: Jan full_name: van Roestel, Jan last_name: van Roestel - first_name: Kevin B. full_name: Burdge, Kevin B. last_name: Burdge - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Ingrid full_name: Pelisoli, Ingrid last_name: Pelisoli - first_name: Boris T. full_name: Gänsicke, Boris T. last_name: Gänsicke - first_name: Paula full_name: Szkody, Paula last_name: Szkody - first_name: Scott J. full_name: Kenyon, Scott J. last_name: Kenyon - first_name: Zach full_name: Vanderbosch, Zach last_name: Vanderbosch - first_name: Andrew full_name: Drake, Andrew last_name: Drake - first_name: Lilia full_name: Ferrario, Lilia last_name: Ferrario - first_name: Dayal full_name: Wickramasinghe, Dayal last_name: Wickramasinghe - first_name: Viraj R. full_name: Karambelkar, Viraj R. last_name: Karambelkar - first_name: Stephen full_name: Justham, Stephen last_name: Justham - first_name: Ruediger full_name: Pakmor, Ruediger last_name: Pakmor - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Thomas full_name: Prince, Thomas last_name: Prince - first_name: S. R. full_name: Kulkarni, S. R. last_name: Kulkarni - first_name: Matthew J. full_name: Graham, Matthew J. last_name: Graham - first_name: Frank J. full_name: Masci, Frank J. last_name: Masci - first_name: Steven L. full_name: Groom, Steven L. last_name: Groom - first_name: Josiah full_name: Purdum, Josiah last_name: Purdum - first_name: Richard full_name: Dekany, Richard last_name: Dekany - first_name: Eric C. full_name: Bellm, Eric C. last_name: Bellm citation: ama: Cristea A-A, Caiazzo I, Cunningham T, et al. A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant. Astronomy & Astrophysics. 2026;706. doi:10.1051/0004-6361/202556432 apa: Cristea, A.-A., Caiazzo, I., Cunningham, T., Raymond, J. C., Vennes, S., Kawka, A., … Bellm, E. C. (2026). A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/202556432 chicago: Cristea, Andrei-Alexandru, Ilaria Caiazzo, Tim Cunningham, John C. Raymond, Stephane Vennes, Adela Kawka, Aayush A Desai, et al. “A Half Ring of Ionized Circumstellar Material Trapped in the Magnetosphere of a White Dwarf Merger Remnant.” Astronomy & Astrophysics. EDP Sciences, 2026. https://doi.org/10.1051/0004-6361/202556432. ieee: A.-A. Cristea et al., “A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant,” Astronomy & Astrophysics, vol. 706. EDP Sciences, 2026. ista: Cristea A-A, Caiazzo I, Cunningham T, Raymond JC, Vennes S, Kawka A, Desai AA, Miller DR, Hermes JJ, Fuller J, Heyl J, van Roestel J, Burdge KB, Rodriguez AC, Pelisoli I, Gänsicke BT, Szkody P, Kenyon SJ, Vanderbosch Z, Drake A, Ferrario L, Wickramasinghe D, Karambelkar VR, Justham S, Pakmor R, El-Badry K, Prince T, Kulkarni SR, Graham MJ, Masci FJ, Groom SL, Purdum J, Dekany R, Bellm EC. 2026. A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant. Astronomy & Astrophysics. 706, A188. mla: Cristea, Andrei-Alexandru, et al. “A Half Ring of Ionized Circumstellar Material Trapped in the Magnetosphere of a White Dwarf Merger Remnant.” Astronomy & Astrophysics, vol. 706, A188, EDP Sciences, 2026, doi:10.1051/0004-6361/202556432. short: A.-A. Cristea, I. Caiazzo, T. Cunningham, J.C. Raymond, S. Vennes, A. Kawka, A.A. Desai, D.R. Miller, J.J. Hermes, J. Fuller, J. Heyl, J. van Roestel, K.B. Burdge, A.C. Rodriguez, I. Pelisoli, B.T. Gänsicke, P. Szkody, S.J. Kenyon, Z. Vanderbosch, A. Drake, L. Ferrario, D. Wickramasinghe, V.R. Karambelkar, S. Justham, R. Pakmor, K. El-Badry, T. Prince, S.R. Kulkarni, M.J. Graham, F.J. Masci, S.L. Groom, J. Purdum, R. Dekany, E.C. Bellm, Astronomy & Astrophysics 706 (2026). corr_author: '1' date_created: 2026-02-17T08:12:05Z date_published: 2026-02-10T00:00:00Z date_updated: 2026-04-28T12:01:21Z day: '10' ddc: - '520' department: - _id: IlCa - _id: GradSch doi: 10.1051/0004-6361/202556432 file: - access_level: open_access checksum: 229b688e6e78cab5bb8e2bac366d1575 content_type: application/pdf creator: dernst date_created: 2026-02-23T12:04:37Z date_updated: 2026-02-23T12:04:37Z file_id: '21350' file_name: 2026_AstronomyAstrophysics_Cristea.pdf file_size: 5352853 relation: main_file success: 1 file_date_updated: 2026-02-23T12:04:37Z has_accepted_license: '1' intvolume: ' 706' language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '02' oa: 1 oa_version: Published Version publication: Astronomy & Astrophysics publication_identifier: eissn: - 1432-0746 issn: - 0004-6361 publication_status: published publisher: EDP Sciences quality_controlled: '1' related_material: link: - description: News on ISTA website relation: press_release url: https://ista.ac.at/en/news/twos-company-new-class-of-star-remnants/ status: public title: A half ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd volume: 706 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold _id: '21705' abstract: - lang: eng text: "We report the discovery of ATLAS J101342.5−451656.8 (hereafter ATLAS J1013−4516), an 8.56 minute orbital-period mass-transferring AM Canum Venaticorum (AM CVn) binary with a mean Gaia magnitude of G = 19.51, identified via periodic variability in light curves from the Asteroid Terrestrial-impact Last Alert System (ATLAS) of Gaia white dwarf candidates. Follow-up with the Large Lenslet Array Magellan Spectrograph shows a helium-dominated accretion disk, and high-speed ULTRACAM photometry reveals pronounced primary and secondary eclipses. We construct a decade-long timing baseline leveraging light curves from the ATLAS and Gaia surveys, as well as the high-speed imagers ULTRACAM on the New Energy Telescope and proto-Lightspeed on the Magellan Clay telescope. From this timing baseline, we measure an orbital period derivative of P 1.60 0.07 10 = ± × 12 s s−1. Interpreted in the context of stable mass transfer, the magnitude and sign of P indicate that the orbital evolution is governed by the interplay between gravitationalwave-driven angular-momentum losses and mass transfer, directly probing the donor’s structural response to mass loss. We constrain the accretor and donor mass based on stable mass-transfer arguments assuming angularmomentum loss dominated by gravitational-wave emission, allowing us to infer the characteristic gravitational\r\nwave strain of the binary for future space-based GW observatories such as the Laser Interferometer Space Antenna (LISA). We predict a characteristic strain corresponding to a 4 yr LISA signal-to-noise ratio ≳10, establishing ATLAS J1013−4516 as a strong prospective LISA source that will probe long-term orbital evolution in the mass-transferring regime." acknowledgement: This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889 and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen’s University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and the Millennium Institute of Astrophysics (MAS), Chile. VSD and ULTRACAM are supported by STFC grant ST/Z000033/1. J.G.M. gratefully acknowledges support from the Heising-Simons Foundation and the Pappalardo family through the MIT Pappalardo Fellowship in Physics. article_number: '237' article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Emma T. full_name: Chickles, Emma T. last_name: Chickles - first_name: Joheen full_name: Chakraborty, Joheen last_name: Chakraborty - first_name: Kevin B. full_name: Burdge, Kevin B. last_name: Burdge - first_name: Vik S. full_name: Dhillon, Vik S. last_name: Dhillon - first_name: Paul full_name: Draghis, Paul last_name: Draghis - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Matthew J. full_name: Green, Matthew J. last_name: Green - first_name: Aaron full_name: Householder, Aaron last_name: Householder - first_name: Sarah full_name: Hughes, Sarah last_name: Hughes - first_name: Christopher full_name: Layden, Christopher last_name: Layden - first_name: Stuart P. full_name: Littlefair, Stuart P. last_name: Littlefair - first_name: James full_name: Munday, James last_name: Munday - first_name: Ingrid full_name: Pelisoli, Ingrid last_name: Pelisoli - first_name: Maya S. full_name: Redden, Maya S. last_name: Redden - first_name: John full_name: Tonry, John last_name: Tonry - first_name: Joannes C full_name: van Roestel, Joannes C id: 4d122fc8-6083-11f0-87a5-97d68b860333 last_name: van Roestel - first_name: Francesco Elio full_name: Angile, Francesco Elio last_name: Angile - first_name: Alex J. full_name: Brown, Alex J. last_name: Brown - first_name: Noel Castro full_name: Segura, Noel Castro last_name: Segura - first_name: Jack full_name: Dinsmore, Jack last_name: Dinsmore - first_name: Martin full_name: Dyer, Martin last_name: Dyer - first_name: Gabor full_name: Furesz, Gabor last_name: Furesz - first_name: Michelle full_name: Gabutti, Michelle last_name: Gabutti - first_name: James full_name: Garbutt, James last_name: Garbutt - first_name: Juliana full_name: García-Mejía, Juliana last_name: García-Mejía - first_name: Daniel full_name: Jarvis, Daniel last_name: Jarvis - first_name: Mark R. full_name: Kennedy, Mark R. last_name: Kennedy - first_name: Paul full_name: Kerry, Paul last_name: Kerry - first_name: James full_name: Mccormac, James last_name: Mccormac - first_name: Geoffrey full_name: Mo, Geoffrey last_name: Mo - first_name: Dave full_name: Osip, Dave last_name: Osip - first_name: Steven full_name: Parsons, Steven last_name: Parsons - first_name: Eleanor full_name: Pike, Eleanor last_name: Pike - first_name: John J. full_name: Piotrowski, John J. last_name: Piotrowski - first_name: Roger W. full_name: Romani, Roger W. last_name: Romani - first_name: David full_name: Sahman, David last_name: Sahman - first_name: Rob full_name: Simcoe, Rob last_name: Simcoe citation: ama: Chickles ET, Chakraborty J, Burdge KB, et al. An eclipsing 8.56 minutes orbital period mass-transferring binary. The Astrophysical Journal. 2026;1000(2). doi:10.3847/1538-4357/ae4871 apa: Chickles, E. T., Chakraborty, J., Burdge, K. B., Dhillon, V. S., Draghis, P., El-Badry, K., … Simcoe, R. (2026). An eclipsing 8.56 minutes orbital period mass-transferring binary. The Astrophysical Journal. IOP Publishing. https://doi.org/10.3847/1538-4357/ae4871 chicago: Chickles, Emma T., Joheen Chakraborty, Kevin B. Burdge, Vik S. Dhillon, Paul Draghis, Kareem El-Badry, Matthew J. Green, et al. “An Eclipsing 8.56 Minutes Orbital Period Mass-Transferring Binary.” The Astrophysical Journal. IOP Publishing, 2026. https://doi.org/10.3847/1538-4357/ae4871. ieee: E. T. Chickles et al., “An eclipsing 8.56 minutes orbital period mass-transferring binary,” The Astrophysical Journal, vol. 1000, no. 2. IOP Publishing, 2026. ista: Chickles ET, Chakraborty J, Burdge KB, Dhillon VS, Draghis P, El-Badry K, Green MJ, Householder A, Hughes S, Layden C, Littlefair SP, Munday J, Pelisoli I, Redden MS, Tonry J, van Roestel JC, Angile FE, Brown AJ, Segura NC, Dinsmore J, Dyer M, Furesz G, Gabutti M, Garbutt J, García-Mejía J, Jarvis D, Kennedy MR, Kerry P, Mccormac J, Mo G, Osip D, Parsons S, Pike E, Piotrowski JJ, Romani RW, Sahman D, Simcoe R. 2026. An eclipsing 8.56 minutes orbital period mass-transferring binary. The Astrophysical Journal. 1000(2), 237. mla: Chickles, Emma T., et al. “An Eclipsing 8.56 Minutes Orbital Period Mass-Transferring Binary.” The Astrophysical Journal, vol. 1000, no. 2, 237, IOP Publishing, 2026, doi:10.3847/1538-4357/ae4871. short: E.T. Chickles, J. Chakraborty, K.B. Burdge, V.S. Dhillon, P. Draghis, K. El-Badry, M.J. Green, A. Householder, S. Hughes, C. Layden, S.P. Littlefair, J. Munday, I. Pelisoli, M.S. Redden, J. Tonry, J.C. van Roestel, F.E. Angile, A.J. Brown, N.C. Segura, J. Dinsmore, M. Dyer, G. Furesz, M. Gabutti, J. Garbutt, J. García-Mejía, D. Jarvis, M.R. Kennedy, P. Kerry, J. Mccormac, G. Mo, D. Osip, S. Parsons, E. Pike, J.J. Piotrowski, R.W. Romani, D. Sahman, R. Simcoe, The Astrophysical Journal 1000 (2026). date_created: 2026-04-12T22:01:47Z date_published: 2026-04-01T00:00:00Z date_updated: 2026-05-04T06:37:12Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.3847/1538-4357/ae4871 external_id: arxiv: - '2601.07925' file: - access_level: open_access checksum: c8f64a78f36224d8e0ea1f324e43e389 content_type: application/pdf creator: dernst date_created: 2026-05-04T06:36:00Z date_updated: 2026-05-04T06:36:00Z file_id: '21782' file_name: 2026_AstrophysicalJournal_Chickles.pdf file_size: 1225916 relation: main_file success: 1 file_date_updated: 2026-05-04T06:36:00Z has_accepted_license: '1' intvolume: ' 1000' issue: '2' language: - iso: eng month: '04' oa: 1 oa_version: Published Version publication: The Astrophysical Journal publication_identifier: eissn: - 1538-4357 issn: - 0004-637X publication_status: published publisher: IOP Publishing quality_controlled: '1' scopus_import: '1' status: public title: An eclipsing 8.56 minutes orbital period mass-transferring binary tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 1000 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '21725' abstract: - lang: eng text: "The initial–final mass relation (IFMR) links a star’s birth mass to the mass of its white dwarf (WD) remnant, providing key constraints on stellar evolution. Open clusters offer the most straightforward way to empirically determine the IFMR, as their well-defined ages allow for direct progenitor lifetime estimates. We construct the most comprehensive open cluster WD IFMR to date by combining new spectroscopy of 22 WDs with an extensive literature review of WDs with strong cluster associations. To minimize systematics, we restrict our analysis to spectroscopically confirmed hydrogen-atmosphere (DA) WDs consistent with single-stellar origins. We separately analyze a subset with reliable Gaia-based astrometric membership assessments, as well as a full sample that adds WDs with strong cluster associations whose membership cannot be reliably assessed with Gaia. The Gaia-based sample includes 69 spectroscopically confirmed DA WDs, more than doubling the sample size of previous Gaia-based open cluster IFMRs. The full sample, which includes 53 additional literature WDs,\r\nincreases the total number of cluster WDs by over 50% relative to earlier works. We provide functional forms for both the Gaia-based and full-sample IFMRs. The Gaia-based result useful for Mi � 2.67 M⊙ is Mf = [0.179 0.100H (Mi 3.84 M )] × (Mi 3.84 M ) + 0.628 M , where H(x) is the Heaviside step function. Comparing our IFMR to recent literature, we identify significant deviations from best-fit IFMRs derived from both Gaia-based volume-limited samples of field WDs and double WD binaries, with the largest discrepancy occurring for initial masses of about 5 M⊙." acknowledgement: "The authors would like to thank the anonymous referee for their constructive feedback, which helped improve the clarify of the manuscript. This work was supported in part by the Natural Sciences and Engineering Research Council of Canada Discovery grants Nos. DG-RGPIN-2022-03051 and DG-RGPIN-2023-04486. This research received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program number 101002408 (MOS100PC). This work includes results based on observations obtained at the international Gemini Observatory, a program of NSF’s NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Gemini spectra were processed using the DRAGONS package (K. Labrie et al. 2023). LRIS spectra were reduced using the Lpipe pipeline (D. A. Perley 2019).\r\n\r\nFacilities: Gaia - (DR2 & DR3), Gemini:Gillett - Gillett Gemini North Telescope (GMOS-N), Gemini:South - Gemini South Telescope (GMOS-S), Keck:I - KECK I Telescope (LRIS).\r\n\r\nSoftware: Astropy (Astropy Collaboration et al. 2013,2018, 2022), emcee (D. Foreman-Mackey et al. 2013)." article_number: '69' article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: David R. full_name: Miller, David R. last_name: Miller - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Jeremy full_name: Heyl, Jeremy last_name: Heyl - first_name: Harvey B. full_name: Richer, Harvey B. last_name: Richer - first_name: Mark A. full_name: Hollands, Mark A. last_name: Hollands - first_name: Pier Emmanuel full_name: Tremblay, Pier Emmanuel last_name: Tremblay - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Zachary P. full_name: Vanderbosch, Zachary P. last_name: Vanderbosch citation: ama: Miller DR, Caiazzo I, Heyl J, et al. The White Dwarf initial–final mass relation from open clusters in Gaia DR3. The Astrophysical Journal. 2026;996(1). doi:10.3847/1538-4357/ae18c8 apa: Miller, D. R., Caiazzo, I., Heyl, J., Richer, H. B., Hollands, M. A., Tremblay, P. E., … Vanderbosch, Z. P. (2026). The White Dwarf initial–final mass relation from open clusters in Gaia DR3. The Astrophysical Journal. IOP Publishing. https://doi.org/10.3847/1538-4357/ae18c8 chicago: Miller, David R., Ilaria Caiazzo, Jeremy Heyl, Harvey B. Richer, Mark A. Hollands, Pier Emmanuel Tremblay, Kareem El-Badry, Antonio C. Rodriguez, and Zachary P. Vanderbosch. “The White Dwarf Initial–Final Mass Relation from Open Clusters in Gaia DR3.” The Astrophysical Journal. IOP Publishing, 2026. https://doi.org/10.3847/1538-4357/ae18c8. ieee: D. R. Miller et al., “The White Dwarf initial–final mass relation from open clusters in Gaia DR3,” The Astrophysical Journal, vol. 996, no. 1. IOP Publishing, 2026. ista: Miller DR, Caiazzo I, Heyl J, Richer HB, Hollands MA, Tremblay PE, El-Badry K, Rodriguez AC, Vanderbosch ZP. 2026. The White Dwarf initial–final mass relation from open clusters in Gaia DR3. The Astrophysical Journal. 996(1), 69. mla: Miller, David R., et al. “The White Dwarf Initial–Final Mass Relation from Open Clusters in Gaia DR3.” The Astrophysical Journal, vol. 996, no. 1, 69, IOP Publishing, 2026, doi:10.3847/1538-4357/ae18c8. short: D.R. Miller, I. Caiazzo, J. Heyl, H.B. Richer, M.A. Hollands, P.E. Tremblay, K. El-Badry, A.C. Rodriguez, Z.P. Vanderbosch, The Astrophysical Journal 996 (2026). date_created: 2026-04-12T22:01:52Z date_published: 2026-01-01T00:00:00Z date_updated: 2026-04-13T08:39:39Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.3847/1538-4357/ae18c8 external_id: arxiv: - '2510.24877' file: - access_level: open_access checksum: 65a8237a519188af83b6dc4d47ad85fa content_type: application/pdf creator: dernst date_created: 2026-04-13T08:36:50Z date_updated: 2026-04-13T08:36:50Z file_id: '21733' file_name: 2026_AstrophysicalJournal_Miller.pdf file_size: 19310053 relation: main_file success: 1 file_date_updated: 2026-04-13T08:36:50Z has_accepted_license: '1' intvolume: ' 996' issue: '1' keyword: - White dwarf stars - Open star clusters - Compact objects - Stellar evolution language: - iso: eng month: '01' oa: 1 oa_version: Published Version publication: The Astrophysical Journal publication_identifier: eissn: - 1538-4357 issn: - 0004-637X publication_status: published publisher: IOP Publishing quality_controlled: '1' scopus_import: '1' status: public title: The White Dwarf initial–final mass relation from open clusters in Gaia DR3 tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 996 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold _id: '21745' abstract: - lang: eng text: 'The small DAHe and DAe spectral classes comprise isolated, hydrogen-dominated atmosphere white dwarfs that exhibit variable photometric flux and Balmer line emission. These mysterious systems offer unique insight into the complex interplay between magnetic fields, stellar rotation and atmospheric activity in single white dwarfs. DAHe stars have detectable magnetic fields through Zeeman-split spectral lines, whereas DAe stars lack such splitting. We report the first discovery and characterization of magnetism in the DAe white dwarf WD J165335.21−100116.33 with new time-resolved spectropolarimetry from FORS2. We detect a weak but variable longitudinal magnetic field with values Bz > −9.2 ± 2.4 kG and Bz < −2.2 ± 1.0 kG. Independent ZTF and ATLAS photometry reveal a consistent period of P = 80.3070 ± 0.0007 h. Time-resolved optical spectroscopy obtained with six ground-based instruments demonstrates strong modulation in the strength of the Hα and Hβ Balmer line emission with P = 80.2922 ± 0.0108 h. The photometric flux and Balmer emission strength vary in antiphase, with the strongest magnetic detections coinciding with phases of low photometric flux and strong line emission. These characteristicssupport the theory that a magnetically active, temperature-inverted spot/region is producing an optically thin chromospheric emission region. Comparison with other DAe and DAHe white dwarfsreveals all systems have a strikingly similar antiphase phenomenology, reinforcing the theory that they are subject to a unified physical mechanism. With the detection of a weak magnetic field, we reclassify WD J165335.21−100116.33 as a low-field DAHe white dwarf. ' acknowledgement: "This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Grant agreement numbers 101002408). The observationsfrom the FOcal Reducer/low dispersion Spectrograph 2 (FORS2) instrument were collected at the European Southern Observatory (ESO) under ESO programme(s) 113.26ES.001. This work has made use of data from the European Space\r\nAgency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/conso\r\nrtium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and\r\nHumboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University\r\nof Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work has made use of data from the Asteroid Terrestrialimpact Last Alert System (ATLAS) project. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen’s University Belfast, the Space Telescope Science Institute, the South African\r\nAstronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile.\r\nThis work makes use of observations from the Las Cumbres Observatory global telescope network. Research at Lick Observatory is partially supported by a generous gift from Google. A major upgrade of the Kast spectrograph on the Shane 3 m telescope at Lick Observatory was made possible through generous gifts from William and Marina Kast as well as the Heising–Simons Foundation. The Isaac Newton Telescope is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile. Observations reported here were obtained at the Multiple Mirror Telescope (MMT) Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. Based on observations collected at Centro Astronómico Hispano en Andalucía (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC)." article_number: stag505 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Abbigail K. full_name: Elms, Abbigail K. last_name: Elms - first_name: Stefano full_name: Bagnulo, Stefano last_name: Bagnulo - first_name: Pier Emmanuel full_name: Tremblay, Pier Emmanuel last_name: Tremblay - first_name: Tim full_name: Cunningham, Tim last_name: Cunningham - first_name: James full_name: Munday, James last_name: Munday - first_name: John full_name: Landstreet, John last_name: Landstreet - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Carl full_name: Melis, Carl last_name: Melis - first_name: Viktoria full_name: Pinter, Viktoria last_name: Pinter - first_name: Alycia full_name: Weinberger, Alycia last_name: Weinberger citation: ama: Elms AK, Bagnulo S, Tremblay PE, et al. Detection of a weak magnetic field in the Balmer emission line white dwarf WDJ1653−1001. Monthly Notices of the Royal Astronomical Society. 2026;548(1). doi:10.1093/mnras/stag505 apa: Elms, A. K., Bagnulo, S., Tremblay, P. E., Cunningham, T., Munday, J., Landstreet, J., … Weinberger, A. (2026). Detection of a weak magnetic field in the Balmer emission line white dwarf WDJ1653−1001. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/stag505 chicago: Elms, Abbigail K., Stefano Bagnulo, Pier Emmanuel Tremblay, Tim Cunningham, James Munday, John Landstreet, Kareem El-Badry, et al. “Detection of a Weak Magnetic Field in the Balmer Emission Line White Dwarf WDJ1653−1001.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2026. https://doi.org/10.1093/mnras/stag505. ieee: A. K. Elms et al., “Detection of a weak magnetic field in the Balmer emission line white dwarf WDJ1653−1001,” Monthly Notices of the Royal Astronomical Society, vol. 548, no. 1. Oxford University Press, 2026. ista: Elms AK, Bagnulo S, Tremblay PE, Cunningham T, Munday J, Landstreet J, El-Badry K, Caiazzo I, Melis C, Pinter V, Weinberger A. 2026. Detection of a weak magnetic field in the Balmer emission line white dwarf WDJ1653−1001. Monthly Notices of the Royal Astronomical Society. 548(1), stag505. mla: Elms, Abbigail K., et al. “Detection of a Weak Magnetic Field in the Balmer Emission Line White Dwarf WDJ1653−1001.” Monthly Notices of the Royal Astronomical Society, vol. 548, no. 1, stag505, Oxford University Press, 2026, doi:10.1093/mnras/stag505. short: A.K. Elms, S. Bagnulo, P.E. Tremblay, T. Cunningham, J. Munday, J. Landstreet, K. El-Badry, I. Caiazzo, C. Melis, V. Pinter, A. Weinberger, Monthly Notices of the Royal Astronomical Society 548 (2026). date_created: 2026-04-19T22:07:42Z date_published: 2026-05-01T00:00:00Z date_updated: 2026-05-04T12:11:53Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1093/mnras/stag505 external_id: arxiv: - '2603.12048' file: - access_level: open_access checksum: 75c48d70d10a9a48875f577e04da80bc content_type: application/pdf creator: dernst date_created: 2026-05-04T12:10:40Z date_updated: 2026-05-04T12:10:40Z file_id: '21794' file_name: 2026_MNRAS_Elms.pdf file_size: 4991495 relation: main_file success: 1 file_date_updated: 2026-05-04T12:10:40Z has_accepted_license: '1' intvolume: ' 548' issue: '1' language: - iso: eng month: '05' oa: 1 oa_version: Published Version publication: Monthly Notices of the Royal Astronomical Society publication_identifier: eissn: - 1365-2966 issn: - 0035-8711 publication_status: published publisher: Oxford University Press quality_controlled: '1' scopus_import: '1' status: public title: Detection of a weak magnetic field in the Balmer emission line white dwarf WDJ1653−1001 tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 548 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold _id: '21780' abstract: - lang: eng text: It is predicted that half or more of all cataclysmic variables (CVs) should have evolved past the period minimum and now exist as so-called period bouncers where a white dwarf should be accreting from a Roche lobe filling substellar companion. However, this prediction stands in stark contrast to observations, where only a few per cent of CVs are found in this evolutionary phase. A potential solution to this discrepancy is that a magnetic field emerges from within the white dwarf after the system has reached the period minimum. The transfer of angular momentum from the spin of the white dwarf into the orbit then pushes the two stars apart, detaching them for potentially billions of years. Here we present the discovery of ZTF J021804.16+071152.93, a detached 0.69 +- 0.01 M⁠, 19 MG magnetic white dwarf plus 37 +- 5MJup brown dwarf binary with an orbital period of 1.7 h. The kinematics of the system indicate that it is a high probability member of the Galactic thick disc. However, this strongly disagrees with the much younger age of the system obtained from the white dwarf parameters, implying that the system may have been accreting in the past. This system is therefore consistent with having detached as a result of the emergence of the magnetic field of the white dwarf when the system was still mass transferring, and may represent the ultimate fate for many (perhaps even most) CVs. acknowledgement: "The results presented in this paper are based on observations collected at the European Southern Observatory under programme IDs 113.D-0277 and 114.D-0066 and on observations made with the Gran Telescopio Canarias (programme ID GTC119-23B), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma.\r\n\r\nSGP acknowledges support by the Science and Technology Facilities Council (grant ST/B001174/1). ARM acknowledges support from MINECO under the PID2023-148661NB-I00 grant and by the AGAUR/Generalitat de Catalunya grant SGR-386/2021. RMO was funded by INTA through grant PRE-OBSERVATORIO and acknowledges support from project PID2023-146210NB-I00 funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU. MZ acknowledges support from FONDECYT (grants 1250525 and 1221059). VSD and HiPERCAM were funded by the Science and Technology Facilities Council (grant ST/Z000033/1). MRS thanks for support from FONDECYT (grant No. 1221059). This project received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Grant agreement numbers 101002408-MOS100PC)." article_number: stag521 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: S. G. full_name: Parsons, S. G. last_name: Parsons - first_name: A. J. full_name: Brown, A. J. last_name: Brown - first_name: S. L. full_name: Casewell, S. L. last_name: Casewell - first_name: S. P. full_name: Littlefair, S. P. last_name: Littlefair - first_name: Joannes C full_name: van Roestel, Joannes C id: 4d122fc8-6083-11f0-87a5-97d68b860333 last_name: van Roestel - first_name: A. full_name: Rebassa-Mansergas, A. last_name: Rebassa-Mansergas - first_name: R. full_name: Murillo-Ojeda, R. last_name: Murillo-Ojeda - first_name: M. full_name: Zorotovic, M. last_name: Zorotovic - first_name: M. R. full_name: Schreiber, M. R. last_name: Schreiber - first_name: S. full_name: Bagnulo, S. last_name: Bagnulo - first_name: M. A. full_name: Stroet, M. A. last_name: Stroet - first_name: N. full_name: Castro Segura, N. last_name: Castro Segura - first_name: V. S. full_name: Dhillon, V. S. last_name: Dhillon - first_name: M. J. full_name: Dyer, M. J. last_name: Dyer - first_name: J. A. full_name: Garbutt, J. A. last_name: Garbutt - first_name: M. J. full_name: Green, M. J. last_name: Green - first_name: D. full_name: Jarvis, D. last_name: Jarvis - first_name: M. R. full_name: Kennedy, M. R. last_name: Kennedy - first_name: P. full_name: Kerry, P. last_name: Kerry - first_name: J. full_name: Mccormac, J. last_name: Mccormac - first_name: J. full_name: Munday, J. last_name: Munday - first_name: I. full_name: Pelisoli, I. last_name: Pelisoli - first_name: E. full_name: Pike, E. last_name: Pike - first_name: D. I. full_name: Sahman, D. I. last_name: Sahman - first_name: A. full_name: Yates, A. last_name: Yates citation: ama: 'Parsons SG, Brown AJ, Casewell SL, et al. ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables. Monthly Notices of the Royal Astronomical Society. 2026;547(4). doi:10.1093/mnras/stag521' apa: 'Parsons, S. G., Brown, A. J., Casewell, S. L., Littlefair, S. P., van Roestel, J. C., Rebassa-Mansergas, A., … Yates, A. (2026). ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/stag521' chicago: 'Parsons, S. G., A. J. Brown, S. L. Casewell, S. P. Littlefair, Joannes C van Roestel, A. Rebassa-Mansergas, R. Murillo-Ojeda, et al. “ZTF J021804.16+071152.93: A Dead Cataclysmic Variable and Potential Solution to the Missing Period Bouncer Cataclysmic Variables.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2026. https://doi.org/10.1093/mnras/stag521.' ieee: 'S. G. Parsons et al., “ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables,” Monthly Notices of the Royal Astronomical Society, vol. 547, no. 4. Oxford University Press, 2026.' ista: 'Parsons SG, Brown AJ, Casewell SL, Littlefair SP, van Roestel JC, Rebassa-Mansergas A, Murillo-Ojeda R, Zorotovic M, Schreiber MR, Bagnulo S, Stroet MA, Castro Segura N, Dhillon VS, Dyer MJ, Garbutt JA, Green MJ, Jarvis D, Kennedy MR, Kerry P, Mccormac J, Munday J, Pelisoli I, Pike E, Sahman DI, Yates A. 2026. ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables. Monthly Notices of the Royal Astronomical Society. 547(4), stag521.' mla: 'Parsons, S. G., et al. “ZTF J021804.16+071152.93: A Dead Cataclysmic Variable and Potential Solution to the Missing Period Bouncer Cataclysmic Variables.” Monthly Notices of the Royal Astronomical Society, vol. 547, no. 4, stag521, Oxford University Press, 2026, doi:10.1093/mnras/stag521.' short: S.G. Parsons, A.J. Brown, S.L. Casewell, S.P. Littlefair, J.C. van Roestel, A. Rebassa-Mansergas, R. Murillo-Ojeda, M. Zorotovic, M.R. Schreiber, S. Bagnulo, M.A. Stroet, N. Castro Segura, V.S. Dhillon, M.J. Dyer, J.A. Garbutt, M.J. Green, D. Jarvis, M.R. Kennedy, P. Kerry, J. Mccormac, J. Munday, I. Pelisoli, E. Pike, D.I. Sahman, A. Yates, Monthly Notices of the Royal Astronomical Society 547 (2026). date_created: 2026-05-03T22:01:37Z date_published: 2026-04-01T00:00:00Z date_updated: 2026-05-07T07:51:58Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1093/mnras/stag521 external_id: arxiv: - '2603.12888' file: - access_level: open_access checksum: a64094199db4dedb12fc121b7c65fe97 content_type: application/pdf creator: dernst date_created: 2026-05-07T07:51:06Z date_updated: 2026-05-07T07:51:06Z file_id: '21834' file_name: 2026_MNRAS_Parsons.pdf file_size: 5955512 relation: main_file success: 1 file_date_updated: 2026-05-07T07:51:06Z has_accepted_license: '1' intvolume: ' 547' issue: '4' language: - iso: eng month: '04' oa: 1 oa_version: Published Version publication: Monthly Notices of the Royal Astronomical Society publication_identifier: eissn: - 1365-2966 issn: - 0035-8711 publication_status: published publisher: Oxford University Press quality_controlled: '1' scopus_import: '1' status: public title: 'ZTF J021804.16+071152.93: A dead cataclysmic variable and potential solution to the missing period bouncer cataclysmic variables' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 547 year: '2026' ... --- OA_place: publisher OA_type: hybrid PlanS_conform: '1' _id: '21842' abstract: - lang: eng text: "AM CVn stars are ultra-compact semi-detached binaries consisting of a white dwarf primary and a hydrogen-depleted secondary. In this\r\npaper, we present spectroscopic and photometric results of 15 transient sources pre-classified as AM CVn candidates. Our analysis confirms\r\n9 systems of the type AM CVn, 3 hydrogen-rich cataclysmic variables (accreting white dwarfs with near-main-sequence stars for donors),\r\nand 3 systems that could be evolved cataclysmic variables. Eight of the AM CVn stars are analysed spectroscopically for the first time,\r\nwhich increases the number of spectroscopically confirmed AM CVns by about 10%. TESS data revealed the orbital period of the AM CVn\r\nstar ASASSN-20pv to be Porb =27.282 min, which helps to constrain the possible values of its mass ratio. TESS also helped to determine\r\nthe superhump periods of one AM CVn star (ASASSN-19ct, Psh =30.94 min) and two cataclysmic variables we classify as WZ Sge stars\r\n(Psh =90.77 min for ZTF18aaaasnn and Psh =91.6min for ASASSN-15na).We identified very different abundances in the spectra of theAM\r\nCVns binaries ASASSN-15kf and ASASSN-20pv (both Porb ∼27.5min), suggesting different type of donors. Six of the studied AMCVns are\r\nX-ray sources, which helped to determine their mass accretion rates. Photometry shows that the duration of all the superoutbursts detected\r\nin the AM CVns is consistent with expectations from the disc instability model. Finally, we provide refined criteria for the identification of\r\nnew systems using all-sky surveys such as LSST." acknowledgement: "We are grateful to the anonymous referee for providing\r\nus with useful comments and suggestions that improved our manuscript.\r\nJK and LRS acknowledge support from NASA grants NNH22ZDA001N-6152\r\nand 80NSSC24K0638. MPM is partially supported by the Swiss National\r\nScience Foundation IZSTZ0_216537 and by UNAM PAPIIT-IG101224. Based\r\non observations obtained at the international Gemini Observatory, a program\r\nof NSF NOIRLab, which is managed by the Association of Universities for\r\nResearch in Astronomy (AURA) under a cooperative agreement with the U.S.\r\nNational Science Foundation on behalf of the Gemini Observatory partnership:\r\nthe U.S. National Science Foundation (United States), National Research\r\nCouncil (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério\r\nda Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea\r\nAstronomy and Space Science Institute (Republic of Korea). The Gemini\r\ndata were obtained from programs GN-2023B-Q-310 and GS-2024A-Q-311\r\n(PI: Rivera Sandoval) and processed using DRAGONS (Data Reduction for\r\nAstronomy from Gemini Observatory North and South) The Digitized Sky\r\nSurveys were produced at the Space Telescope Science Institute under U.S.\r\nGovernment grant NAG W-2166. The images of these surveys are based on\r\nphotographic data obtained using the Oschin Schmidt Telescope on Palomar\r\nMountain and the UK Schmidt Telescope. The plates were processed into the\r\npresent compressed digital form with the permission of these institutions.\r\nThe National Geographic Society – Palomar Observatory Sky Atlas (POSS-I)\r\nwas made by the California Institute of Technology with grants from the\r\nNational Geographic Society. The Second Palomar Observatory Sky Survey\r\n(POSS-II) was made by the California Institute of Technology with funds\r\nfrom the National Science Foundation, the National Geographic Society, the\r\nSloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak\r\nCorporation. The Oschin Schmidt Telescope is operated by the California\r\nInstitute of Technology and Palomar Observatory. The UK Schmidt Telescope\r\nwas operated by the Royal Observatory Edinburgh, with funding from the\r\nUK Science and Engineering Research Council (later the UK Particle Physics\r\nand Astronomy Research Council), until 1988 June, and thereafter by the\r\nAnglo-Australian Observatory. The blue plates of the southern Sky Atlas\r\nand its Equatorial Extension (together known as the SERC-J), as well as the\r\nEquatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken\r\nwith the UK Schmidt. Supplemental funding for sky-survey work at the ST\r\nScI is provided by the European Southern Observatory. Based on observations\r\nobtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope\r\nat the Palomar Observatory as part of the Zwicky Transient Facility project.\r\nZTF is supported by the National Science Foundation under Grants No. AST-\r\n1440341 and AST-2034437 and a collaboration including current partners\r\nCaltech, IPAC, the Oskar Klein Center at Stockholm University, the University\r\nof Maryland, University of California, Berkeley, the University of Wisconsin\r\nat Milwaukee, University of Warwick, Ruhr University, Cornell University,\r\nNorthwestern University, and Drexel University. Operations are conducted\r\nby COO, IPAC, and UW. This work has used data from the European\r\nSpace Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia),\r\nprocessed by the Gaia Data Processing and Analysis Consortium (DPAC,\r\nhttps://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the\r\nDPAC has been provided by national institutions, in particular, the institutions\r\nparticipating in the Gaia Multilateral Agreement. We acknowledge with\r\nthanks the variable star observations from the AAVSO International Database\r\ncontributed by observers worldwide and used in this research. This paper\r\nincludes data collected by the TESS mission. Funding for the TESS mission\r\nis provided by the NASA Science Mission Directorate. Some of the data\r\npresented in this paper were obtained from the B. Mikulski Archive for Space\r\nTelescopes (MAST). This research has made use of the SIMBAD database,\r\noperated at CDS, Strasbourg, France. This research has made use of ‘Aladin\r\nsky atlas’ developed at CDS, Strasbourg Observatory, France. This research\r\nhas made use of the VizieR catalogue access tool, CDS, Strasbourg, France." article_number: e052 article_processing_charge: Yes (in subscription journal) article_type: original author: - first_name: Jan full_name: Kára, Jan last_name: Kára - first_name: Liliana full_name: Rivera Sandoval, Liliana last_name: Rivera Sandoval - first_name: Wendy full_name: Mendoza, Wendy last_name: Mendoza - first_name: Thomas full_name: Maccarone, Thomas last_name: Maccarone - first_name: Manuel full_name: Pichardo Marcano, Manuel last_name: Pichardo Marcano - first_name: Luis E. full_name: Salazar Manzano, Luis E. last_name: Salazar Manzano - first_name: Ryan J. full_name: Oelkers, Ryan J. last_name: Oelkers - first_name: Joannes C full_name: van Roestel, Joannes C id: 4d122fc8-6083-11f0-87a5-97d68b860333 last_name: van Roestel citation: ama: Kára J, Rivera Sandoval L, Mendoza W, et al. A study of transients from ground-based surveys reveals new ultra-compact accreting white dwarf binaries. Publications of the Astronomical Society of Australia. 2026;43. doi:10.1017/pasa.2026.10184 apa: Kára, J., Rivera Sandoval, L., Mendoza, W., Maccarone, T., Pichardo Marcano, M., Salazar Manzano, L. E., … van Roestel, J. C. (2026). A study of transients from ground-based surveys reveals new ultra-compact accreting white dwarf binaries. Publications of the Astronomical Society of Australia. Cambridge University Press. https://doi.org/10.1017/pasa.2026.10184 chicago: Kára, Jan, Liliana Rivera Sandoval, Wendy Mendoza, Thomas Maccarone, Manuel Pichardo Marcano, Luis E. Salazar Manzano, Ryan J. Oelkers, and Joannes C van Roestel. “A Study of Transients from Ground-Based Surveys Reveals New Ultra-Compact Accreting White Dwarf Binaries.” Publications of the Astronomical Society of Australia. Cambridge University Press, 2026. https://doi.org/10.1017/pasa.2026.10184. ieee: J. Kára et al., “A study of transients from ground-based surveys reveals new ultra-compact accreting white dwarf binaries,” Publications of the Astronomical Society of Australia, vol. 43. Cambridge University Press, 2026. ista: Kára J, Rivera Sandoval L, Mendoza W, Maccarone T, Pichardo Marcano M, Salazar Manzano LE, Oelkers RJ, van Roestel JC. 2026. A study of transients from ground-based surveys reveals new ultra-compact accreting white dwarf binaries. Publications of the Astronomical Society of Australia. 43, e052. mla: Kára, Jan, et al. “A Study of Transients from Ground-Based Surveys Reveals New Ultra-Compact Accreting White Dwarf Binaries.” Publications of the Astronomical Society of Australia, vol. 43, e052, Cambridge University Press, 2026, doi:10.1017/pasa.2026.10184. short: J. Kára, L. Rivera Sandoval, W. Mendoza, T. Maccarone, M. Pichardo Marcano, L.E. Salazar Manzano, R.J. Oelkers, J.C. van Roestel, Publications of the Astronomical Society of Australia 43 (2026). date_created: 2026-05-07T08:55:00Z date_published: 2026-03-27T00:00:00Z date_updated: 2026-05-12T06:57:40Z day: '27' ddc: - '520' department: - _id: IlCa doi: 10.1017/pasa.2026.10184 file: - access_level: open_access checksum: f8f3cd3765948e8b276176c71c9d4e02 content_type: application/pdf creator: dernst date_created: 2026-05-12T06:54:10Z date_updated: 2026-05-12T06:54:10Z file_id: '21862' file_name: 2026_PublAstronomicalSocAustralia_Kara.pdf file_size: 3681016 relation: main_file success: 1 file_date_updated: 2026-05-12T06:54:10Z has_accepted_license: '1' intvolume: ' 43' language: - iso: eng month: '03' oa: 1 oa_version: Published Version publication: Publications of the Astronomical Society of Australia publication_identifier: eissn: - 1448-6083 issn: - 1323-3580 publication_status: published publisher: Cambridge University Press quality_controlled: '1' scopus_import: '1' status: public title: A study of transients from ground-based surveys reveals new ultra-compact accreting white dwarf binaries tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 43 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '21897' abstract: - lang: eng text: Ultracompact binary systems, consisting of two compact objects in an orbit $\lesssim 0.5 {\rm R}_\odot$, should exhibit measurable rates of orbital period change ($\dot{P} \ne 0$) due to the emission of gravitational waves (GWs). Measurements of $\dot{P}$ have so far been limited to the shortest-period ultracompact binaries ($\lesssim 20$  min). Among the AM CVn-type subclass, several works have proposed the presence of extra angular momentum loss beyond GW emission, with magnetic braking being a widely discussed mechanism. If present, this magnetic braking would dominate the angular momentum loss of AM CVn-type binaries with orbital periods $\gtrsim 30$ min. In this work, we present a long-term eclipse timing study of two AM CVn-type binaries, YZ LMi and Gaia14aae, with respective orbital periods of 28.3 min and 49.7 min and continuous observations since 2006 and 2015. Both systems show $\dot{P}$ consistent with zero within $2\sigma$. Their $3\sigma$ upper limits are $1.1 \times 10^{-13}\, {\rm s \, s}^{-1}$ and $9.7 \times 10^{-14}\, {\rm s \, s}^{-1}$, respectively. These non-detections are most simply explained by a scenario in which secular angular momentum loss is not substantially stronger than GW emission at all orbital periods, but is combined with deviations from the secular $\dot{P}$ whose time-scales span decades but whose amplitude is $\lesssim 10^{-13}\, {\rm s \, s}^{-1}$. Our non-detections of $\dot{P}$ represent a limit on the strength of any enhanced angular momentum loss beyond pure GW emission. acknowledgement: "We are grateful to the anonymousreferee fortheirinsightful comments. MJG thanks Mitch Begelman and the JILA department at the University of Colorado, Boulder, for providing office space at which much of this paper was written. This work is supported in part by the United States National Aeronautics and Space Administration (NASA) under grants\r\n80NSSC24K0436, 80NSSC22K0479, and 80NSSC24K0380, and the United States National Science Foundation (NSF) under grant AST-2508429. VSD and HiPERCAM are funded by the Science and Technology Facilities Council (grant ST/Z000033/1). IP acknowledges support from the Royal Society through a University Research Fellowship (URF\\R1\\231496). This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement numbers 101002408 – MOS100PC). CMC receives funding from United Kingdom Research and Innovation grant numbers ST/X005933/1 and ST/W001934/1. This article is based in part on observations made in the Observatorios de Canarias del Instituto de Astrofísica de Canarias (IAC) with the the William Herschel Telescope (WHT) operated on the island of La Palma by the Isaac Newton Group (ING) in the Observatorio del Roque de los Muchachos. It is also based in part on observations made with the Gran Telescopio Canarias (GTC) under proposal ID GTC18-24A, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. Further data were obtained using the 2.4 m Thai National Telescope (TNT) operated by the National Astronomy Research Institute of Thailand\r\n(NARIT), and the 200-inch Hale Telescope at Palomar Observatory operated by the California Institute of Technology. Software packages used in this work include the ultracam and hipercam reduction pipelines, lcurve (C. M. Copperwheat et al. 2010), numpy, astropy, matplotlib, and emcee (D. Foreman-Mackey et al. 2013)." article_number: stag673 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Matthew J full_name: Green, Matthew J last_name: Green - first_name: Thomas R full_name: Marsh, Thomas R last_name: Marsh - first_name: Joannes C full_name: van Roestel, Joannes C id: 4d122fc8-6083-11f0-87a5-97d68b860333 last_name: van Roestel - first_name: Tin Long Sunny full_name: Wong, Tin Long Sunny last_name: Wong - first_name: Diogo full_name: Belloni, Diogo last_name: Belloni - first_name: Mukremin full_name: Kilic, Mukremin last_name: Kilic - first_name: Elmé full_name: Breedt, Elmé last_name: Breedt - first_name: Alex full_name: Brown, Alex last_name: Brown - first_name: Chris M full_name: Copperwheat, Chris M last_name: Copperwheat - first_name: Anurak full_name: Chakpor, Anurak last_name: Chakpor - first_name: V S full_name: Dhillon, V S last_name: Dhillon - first_name: Noel Castro full_name: Segura, Noel Castro last_name: Segura - first_name: Martin J full_name: Dyer, Martin J last_name: Dyer - first_name: James full_name: Garbutt, James last_name: Garbutt - first_name: Dan full_name: Jarvis, Dan last_name: Jarvis - first_name: Vasu full_name: Kengkriangkrai, Vasu last_name: Kengkriangkrai - first_name: Mark R full_name: Kennedy, Mark R last_name: Kennedy - first_name: Paul full_name: Kerry, Paul last_name: Kerry - first_name: Thomas full_name: Kupfer, Thomas last_name: Kupfer - first_name: S P full_name: Littlefair, S P last_name: Littlefair - first_name: James full_name: McCormac, James last_name: McCormac - first_name: James full_name: Munday, James last_name: Munday - first_name: Steven G full_name: Parsons, Steven G last_name: Parsons - first_name: Eleanor full_name: Pike, Eleanor last_name: Pike - first_name: Ingrid full_name: Pelisoli, Ingrid last_name: Pelisoli - first_name: Pablo full_name: Rodríguez-Gil, Pablo last_name: Rodríguez-Gil - first_name: David I full_name: Sahman, David I last_name: Sahman - first_name: Amalie full_name: Yates, Amalie last_name: Yates citation: ama: Green MJ, Marsh TR, van Roestel JC, et al. No period change in two long-period AM CVn binaries. Monthly Notices of the Royal Astronomical Society. 2026;548(3). doi:10.1093/mnras/stag673 apa: Green, M. J., Marsh, T. R., van Roestel, J. C., Wong, T. L. S., Belloni, D., Kilic, M., … Yates, A. (2026). No period change in two long-period AM CVn binaries. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/stag673 chicago: Green, Matthew J, Thomas R Marsh, Joannes C van Roestel, Tin Long Sunny Wong, Diogo Belloni, Mukremin Kilic, Elmé Breedt, et al. “No Period Change in Two Long-Period AM CVn Binaries.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2026. https://doi.org/10.1093/mnras/stag673. ieee: M. J. Green et al., “No period change in two long-period AM CVn binaries,” Monthly Notices of the Royal Astronomical Society, vol. 548, no. 3. Oxford University Press, 2026. ista: Green MJ, Marsh TR, van Roestel JC, Wong TLS, Belloni D, Kilic M, Breedt E, Brown A, Copperwheat CM, Chakpor A, Dhillon VS, Segura NC, Dyer MJ, Garbutt J, Jarvis D, Kengkriangkrai V, Kennedy MR, Kerry P, Kupfer T, Littlefair SP, McCormac J, Munday J, Parsons SG, Pike E, Pelisoli I, Rodríguez-Gil P, Sahman DI, Yates A. 2026. No period change in two long-period AM CVn binaries. Monthly Notices of the Royal Astronomical Society. 548(3), stag673. mla: Green, Matthew J., et al. “No Period Change in Two Long-Period AM CVn Binaries.” Monthly Notices of the Royal Astronomical Society, vol. 548, no. 3, stag673, Oxford University Press, 2026, doi:10.1093/mnras/stag673. short: M.J. Green, T.R. Marsh, J.C. van Roestel, T.L.S. Wong, D. Belloni, M. Kilic, E. Breedt, A. Brown, C.M. Copperwheat, A. Chakpor, V.S. Dhillon, N.C. Segura, M.J. Dyer, J. Garbutt, D. Jarvis, V. Kengkriangkrai, M.R. Kennedy, P. Kerry, T. Kupfer, S.P. Littlefair, J. McCormac, J. Munday, S.G. Parsons, E. Pike, I. Pelisoli, P. Rodríguez-Gil, D.I. Sahman, A. Yates, Monthly Notices of the Royal Astronomical Society 548 (2026). date_created: 2026-05-20T14:34:03Z date_published: 2026-04-09T00:00:00Z date_updated: 2026-05-21T06:41:41Z day: '09' ddc: - '520' department: - _id: IlCa doi: 10.1093/mnras/stag673 external_id: arxiv: - '2604.06460' file: - access_level: open_access checksum: 2c4463926c5cb84ce555ef2005b52ddd content_type: application/pdf creator: dernst date_created: 2026-05-21T06:37:42Z date_updated: 2026-05-21T06:37:42Z file_id: '21903' file_name: 2026_MNRAS_Green.pdf file_size: 3960296 relation: main_file success: 1 file_date_updated: 2026-05-21T06:37:42Z has_accepted_license: '1' intvolume: ' 548' issue: '3' keyword: - 'binaries: close – stars' - dwarf novae – novae - cataclysmic variables – white dwarfs language: - iso: eng month: '04' oa: 1 oa_version: Published Version publication: Monthly Notices of the Royal Astronomical Society publication_identifier: eissn: - 1365-2966 issn: - 0035-8711 publication_status: published publisher: Oxford University Press quality_controlled: '1' scopus_import: '1' status: public title: No period change in two long-period AM CVn binaries tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 548 year: '2026' ... --- OA_place: publisher OA_type: diamond PlanS_conform: '1' _id: '21160' abstract: - lang: eng text: "Context. AM Canum Venaticorum (AM CVn) stars are ultra-compact binary systems composed of a white dwarf primary accreting from a hydrogen-deficient donor. They play a crucial role in astrophysics as potential progenitors of Type Ia supernovae and as laboratories for gravitational wave studies. However, their formation and evolutionary history remain incomplete. Three formation channels have been discussed in the literature: the white dwarf, He-star, and cataclysmic variable channels.\r\n\r\nAims. The chemical composition of the accretor atmosphere reflects the material transferred from the donor. In this work we took the first accurate measurements of the fundamental parameters of the accreting white dwarf in ZTF J225237.05−051917.4, including the abundances of key elements such as carbon, nitrogen, and silicon, by analysing ultraviolet spectra obtained with the Hubble Space Telescope (HST). These measurements provide new insight into the evolutionary history of the system and, together with existing optical observations, establish it as a benchmark to develop our pipeline, paving the way for its application to a larger sample of AM CVn systems.\r\n\r\nMethods. We determined the binary parameters through photometric analysis and constrained the atmospheric parameters of the white dwarf accretor, including its effective temperature, surface gravity, and chemical abundances, by fitting the HST ultraviolet spectrum with synthetic spectral models. We then inferred the system’s formation channel by comparing the results with theoretical evolutionary models.\r\n\r\nResults. According to our measurements, the accretor’s effective temperature (Teff) is 23 300 ± 600 K and the surface gravity (log g) is 8.4 ± 0.3, which imply an accretor mass (MWD) of 0.86 ± 0.16 M⊙. We find a high nitrogen-to-carbon abundance ratio by mass of > 153.\r\n\r\nConclusions. The accretor is significantly hotter than previous estimates based on simplified blackbody fits to the spectral energy distribution, underscoring the importance of detailed spectral modelling for accurately determining system parameters. Our results show that ultraviolet spectroscopy is well suited to constraining the formation channels of AM CVn systems. Of the three proposed formation channels, the He-star channel can be excluded given the high nitrogen-to-carbon ratio. Our results are consistent with both the white dwarf and cataclysmic variable channels." acknowledgement: "We thank Lars Bildsten for valuable insights and discussions. We acknowledge with thanks the variable star observations from the\r\nAAVSO International Database contributed by observers worldwide and used in this research. We thank the members of the Spanish Observers of Supernovae\r\n(ObSN) group for their valuable photometric contributions. This research was\r\nsupported by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 2121 “Quantum Universe”\r\n– 390833306. Co-funded by the European Union (ERC, CompactBINARIES,\r\n101078773). Views and opinions expressed are however those of the author(s)\r\nonly and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority\r\ncan be held responsible for them. DB acknowledges support from the São Paulo\r\nResearch Foundation (FAPESP), Brazil, Process Numbers #2024/03736-2 and\r\n#2025/00817-4. MRS is supported by Fondecyt (grant 1221059). MJG acknowledges support from the European Research Council through ERC Advanced\r\nGrant No. 101054731, from the National Aeronautics and Space Administration under grants 80NSSC24K0436, 80NSSC22K0479, and 80NSSC24K0380,\r\nand from the National Science Foundation under grant AST-2205736. PJG\r\nis supported by NRF SARChI grant 111692. PR-G acknowledges support by\r\nthe Agencia Estatal de Investigación del Ministerio de Ciencia e Innovación\r\n(MCIN/AEI) and the European Regional Development Fund (ERDF) under grant\r\nPID2021–124879NB–I00. DS is supported by the UK Science and Technology Facilities Council (STFC, grant numbers ST/T007184/1, ST/T003103/1,\r\nand ST/T000406/1). OT acknowledges Proyectos Internos USM 2025, PI-LII2025-03. GT was supported by grants IN109723 from the Programa de Apoyo a\r\nProyectos de Investigación e Innovación Tecnológica (PAPIIT). This project has\r\nreceived funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 101020057)." article_number: A14 article_processing_charge: No article_type: original arxiv: 1 author: - first_name: W. full_name: Yu, W. last_name: Yu - first_name: A. F. full_name: Pala, A. F. last_name: Pala - first_name: T. full_name: Kupfer, T. last_name: Kupfer - first_name: B. T. full_name: Gänsicke, B. T. last_name: Gänsicke - first_name: D. full_name: Koester, D. last_name: Koester - first_name: D. full_name: Belloni, D. last_name: Belloni - first_name: T. L.S. full_name: Wong, T. L.S. last_name: Wong - first_name: M. R. full_name: Schreiber, M. R. last_name: Schreiber - first_name: Joannes C full_name: van Roestel, Joannes C id: 4d122fc8-6083-11f0-87a5-97d68b860333 last_name: van Roestel - first_name: A. J. full_name: Brown, A. J. last_name: Brown - first_name: E. O. full_name: Waagen, E. O. last_name: Waagen - first_name: J. L. full_name: González-Carballo, J. L. last_name: González-Carballo - first_name: S. full_name: Bednarz, S. last_name: Bednarz - first_name: K. full_name: Bernacki, K. last_name: Bernacki - first_name: D. full_name: De Martino, D. last_name: De Martino - first_name: E. full_name: Fernández Mañanes, E. last_name: Fernández Mañanes - first_name: R. full_name: González Farfán, R. last_name: González Farfán - first_name: M. J. full_name: Green, M. J. last_name: Green - first_name: P. J. full_name: Groot, P. J. last_name: Groot - first_name: F. J. full_name: Hambsch, F. J. last_name: Hambsch - first_name: C. full_name: Knigge, C. last_name: Knigge - first_name: J. L. full_name: Martin-Velasco, J. L. last_name: Martin-Velasco - first_name: M. full_name: Morales-Aimar, M. last_name: Morales-Aimar - first_name: G. full_name: Myers, G. last_name: Myers - first_name: R. full_name: Naves Nogues, R. last_name: Naves Nogues - first_name: R. full_name: Poggiani, R. last_name: Poggiani - first_name: A. full_name: Popowicz, A. last_name: Popowicz - first_name: G. full_name: Ramsay, G. last_name: Ramsay - first_name: E. full_name: Reina-Lorenz, E. last_name: Reina-Lorenz - first_name: P. full_name: Rodríguez-Gil, P. last_name: Rodríguez-Gil - first_name: J. L. full_name: Salto-González, J. L. last_name: Salto-González - first_name: E. M. full_name: Sion, E. M. last_name: Sion - first_name: D. full_name: Steeghs, D. last_name: Steeghs - first_name: P. full_name: Szkody, P. last_name: Szkody - first_name: O. full_name: Toloza, O. last_name: Toloza - first_name: G. full_name: Tovmassian, G. last_name: Tovmassian citation: ama: 'Yu W, Pala AF, Kupfer T, et al. The evolutionary history of ultra-compact accreting binaries: I. Chemical abundances and the formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy. Astronomy & Astrophysics. 2026;706. doi:10.1051/0004-6361/202557568' apa: 'Yu, W., Pala, A. F., Kupfer, T., Gänsicke, B. T., Koester, D., Belloni, D., … Tovmassian, G. (2026). The evolutionary history of ultra-compact accreting binaries: I. Chemical abundances and the formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/202557568' chicago: 'Yu, W., A. F. Pala, T. Kupfer, B. T. Gänsicke, D. Koester, D. Belloni, T. L.S. Wong, et al. “The Evolutionary History of Ultra-Compact Accreting Binaries: I. Chemical Abundances and the Formation Channel of the Eclipsing AM CVn System ZTF J225237.05-051917.4 from HST Spectroscopy.” Astronomy & Astrophysics. EDP Sciences, 2026. https://doi.org/10.1051/0004-6361/202557568.' ieee: 'W. Yu et al., “The evolutionary history of ultra-compact accreting binaries: I. Chemical abundances and the formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy,” Astronomy & Astrophysics, vol. 706. EDP Sciences, 2026.' ista: 'Yu W, Pala AF, Kupfer T, Gänsicke BT, Koester D, Belloni D, Wong TLS, Schreiber MR, van Roestel JC, Brown AJ, Waagen EO, González-Carballo JL, Bednarz S, Bernacki K, De Martino D, Fernández Mañanes E, González Farfán R, Green MJ, Groot PJ, Hambsch FJ, Knigge C, Martin-Velasco JL, Morales-Aimar M, Myers G, Naves Nogues R, Poggiani R, Popowicz A, Ramsay G, Reina-Lorenz E, Rodríguez-Gil P, Salto-González JL, Sion EM, Steeghs D, Szkody P, Toloza O, Tovmassian G. 2026. The evolutionary history of ultra-compact accreting binaries: I. Chemical abundances and the formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy. Astronomy & Astrophysics. 706, A14.' mla: 'Yu, W., et al. “The Evolutionary History of Ultra-Compact Accreting Binaries: I. Chemical Abundances and the Formation Channel of the Eclipsing AM CVn System ZTF J225237.05-051917.4 from HST Spectroscopy.” Astronomy & Astrophysics, vol. 706, A14, EDP Sciences, 2026, doi:10.1051/0004-6361/202557568.' short: W. Yu, A.F. Pala, T. Kupfer, B.T. Gänsicke, D. Koester, D. Belloni, T.L.S. Wong, M.R. Schreiber, J.C. van Roestel, A.J. Brown, E.O. Waagen, J.L. González-Carballo, S. Bednarz, K. Bernacki, D. De Martino, E. Fernández Mañanes, R. González Farfán, M.J. Green, P.J. Groot, F.J. Hambsch, C. Knigge, J.L. Martin-Velasco, M. Morales-Aimar, G. Myers, R. Naves Nogues, R. Poggiani, A. Popowicz, G. Ramsay, E. Reina-Lorenz, P. Rodríguez-Gil, J.L. Salto-González, E.M. Sion, D. Steeghs, P. Szkody, O. Toloza, G. Tovmassian, Astronomy & Astrophysics 706 (2026). das_tickbox: '1' date_created: 2026-02-08T23:02:49Z date_published: 2026-02-01T00:00:00Z date_updated: 2026-07-08T06:38:46Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1051/0004-6361/202557568 external_id: arxiv: - '2512.04147' file: - access_level: open_access checksum: 2faec710fd04f927aa43deb57e35c9b2 content_type: application/pdf creator: dernst date_created: 2026-02-16T09:33:56Z date_updated: 2026-02-16T09:33:56Z file_id: '21227' file_name: 2026_AstronomyAstrophysics_Yu.pdf file_size: 4020466 relation: main_file success: 1 file_date_updated: 2026-02-16T09:33:56Z has_accepted_license: '1' intvolume: ' 706' language: - iso: eng month: '02' oa: 1 oa_version: Published Version publication: Astronomy & Astrophysics publication_identifier: eissn: - 1432-0746 issn: - 0004-6361 publication_status: published publisher: EDP Sciences quality_controlled: '1' scopus_import: '1' status: public title: 'The evolutionary history of ultra-compact accreting binaries: I. Chemical abundances and the formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 706 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: diamond PlanS_conform: '1' _id: '21658' abstract: - lang: eng text: Dipolar (ℓ = 1) mixed modes have revealed a surprisingly weak differential rotation between the core and the envelope of evolved solar-like stars. Quadrupolar (ℓ = 2) mixed modes also contain information regarding internal dynamics but are very rarely characterised due to their low amplitude and the challenging identification of adjacent or overlapping rotationally split multiplets affected by near-degeneracy effects. We aim to extend the broadly used asymptotic seismic diagnostics beyond ℓ = 1 mixed modes by developing an analogue asymptotic description of ℓ = 2 mixed modes while explicitly accounting for near-degeneracy effects that distort their rotational multiplets. We have derived a new asymptotic formulation of near-degenerate mixed ℓ = 2 modes that describes off-diagonal terms representing the interaction between modes of adjacent radial orders. This formalism, expressed directly in the mixed-mode basis, provides analytical expressions for the near-degeneracy effects. We implemented the formalism within a global Bayesian mode-fitting framework for a direct fit of all ℓ = 0, 1, 2 modes in the power spectrum density. We were able to asymptotically model the asymmetric rotational splitting present in various radial orders of ℓ = 2 modes observed in young red giant stars without the need for any numerical stellar modelling. We applied our formalism to the Kepler target KIC 7341231, and it yielded core and envelope rotation rates consistent with previous numerical modelling while providing improved constraints from the global and model-independent approach. We also characterised the new target, KIC 8179973, measuring its rotation rate and mixed-mode parameters for the first time. As our framework relies on a direct global fit, it allows for much better precision on the asteroseismic parameters and rotation rate estimates than standard methods, yielding better constraints for rotation inversions. We have placed the first observational constraints on the asymptotic ℓ = 2 mixed-mode parameters (ΔΠ2, q2, and εg, 2), thus paving the way towards the use of asymptotic seismology beyond ℓ = 1 mixed modes. acknowledgement: 'We thank the referee for their careful and constructive report, which has substantially enhanced both the quality and clarity of the manuscript. L. Bugnet and L. Einramhof gratefully acknowledge support from the European Research Council (ERC) under the Horizon Europe programme (Calcifer; Starting Grant agreement N°101165631). While partially funded by the European Union, views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. The authors acknowledge the great support and feedback provided during the redaction of this article by Pr. Rafael García and Pr. Savita Mathur. We would also like to thank Dr. Emily Hatt for her insights on uncertainty estimates. The authors also thank the members of the Asteroseismology and Stellar Dynamics group of the Institute of Science and Technology Austria (ISTA) for very useful discussions: L. Barrault, S.B. Das, K. Smith. This paper includes data collected by the Kepler mission and obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the Kepler mission is provided by the NASA Science Mission Directorate. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. Software: AstroPy (Astropy Collaboration 2013, 2018), Matplotlib (Hunter 2007), NumPy (Harris et al. 2020), SciPy (Virtanen et al. 2020), emcee (Foreman-Mackey et al. 2013), celerite (Foreman-Mackey et al. 2017), slepc4py (Dalcin et al. 2011; Hernandez et al. 2005), KADACS (García et al. 2011), sloscillations (Kuszlewicz et al. 2019, 2023).' article_number: A321 article_processing_charge: No article_type: original arxiv: 1 author: - first_name: Bastien Raymond Bernard full_name: Liagre, Bastien Raymond Bernard id: 662f1873-cab4-11f0-a719-8087d302868d last_name: Liagre - first_name: Aayush A full_name: Desai, Aayush A id: 502cfd30-32c1-11ee-a9a4-d8dad5c6739e last_name: Desai - first_name: Lukas full_name: Einramhof, Lukas id: f1497a1a-72ef-11ef-b75a-fd877bbf6e8c last_name: Einramhof - first_name: Lisa Annabelle full_name: Bugnet, Lisa Annabelle id: d9edb345-f866-11ec-9b37-d119b5234501 last_name: Bugnet orcid: 0000-0003-0142-4000 citation: ama: 'Liagre BRB, Desai AA, Einramhof L, Bugnet LA. Near-degeneracy effects in quadrupolar mixed modes: From an asymptotic description to data fitting. Astronomy & Astrophysics. 2026;707. doi:10.1051/0004-6361/202558023' apa: 'Liagre, B. R. B., Desai, A. A., Einramhof, L., & Bugnet, L. A. (2026). Near-degeneracy effects in quadrupolar mixed modes: From an asymptotic description to data fitting. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/202558023' chicago: 'Liagre, Bastien Raymond Bernard, Aayush A Desai, Lukas Einramhof, and Lisa Annabelle Bugnet. “Near-Degeneracy Effects in Quadrupolar Mixed Modes: From an Asymptotic Description to Data Fitting.” Astronomy & Astrophysics. EDP Sciences, 2026. https://doi.org/10.1051/0004-6361/202558023.' ieee: 'B. R. B. Liagre, A. A. Desai, L. Einramhof, and L. A. Bugnet, “Near-degeneracy effects in quadrupolar mixed modes: From an asymptotic description to data fitting,” Astronomy & Astrophysics, vol. 707. EDP Sciences, 2026.' ista: 'Liagre BRB, Desai AA, Einramhof L, Bugnet LA. 2026. Near-degeneracy effects in quadrupolar mixed modes: From an asymptotic description to data fitting. Astronomy & Astrophysics. 707, A321.' mla: 'Liagre, Bastien Raymond Bernard, et al. “Near-Degeneracy Effects in Quadrupolar Mixed Modes: From an Asymptotic Description to Data Fitting.” Astronomy & Astrophysics, vol. 707, A321, EDP Sciences, 2026, doi:10.1051/0004-6361/202558023.' short: B.R.B. Liagre, A.A. Desai, L. Einramhof, L.A. Bugnet, Astronomy & Astrophysics 707 (2026). corr_author: '1' das_tickbox: '1' date_created: 2026-04-05T22:01:32Z date_published: 2026-03-01T00:00:00Z date_updated: 2026-07-08T06:39:05Z day: '01' ddc: - '520' department: - _id: LiBu - _id: IlCa - _id: GradSch doi: 10.1051/0004-6361/202558023 external_id: arxiv: - '2511.05314 ' file: - access_level: open_access checksum: 560cac19dc70184626b85e71a26ee22e content_type: application/pdf creator: dernst date_created: 2026-04-07T09:00:50Z date_updated: 2026-04-07T09:00:50Z file_id: '21664' file_name: 2026_AstronomyAstrophysics_Liagre.pdf file_size: 12287607 relation: main_file success: 1 file_date_updated: 2026-04-07T09:00:50Z has_accepted_license: '1' intvolume: ' 707' language: - iso: eng month: '03' oa: 1 oa_version: Published Version publication: Astronomy & Astrophysics publication_identifier: eissn: - 1432-0746 issn: - 0004-6361 publication_status: published publisher: EDP Sciences quality_controlled: '1' scopus_import: '1' status: public title: 'Near-degeneracy effects in quadrupolar mixed modes: From an asymptotic description to data fitting' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 707 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold _id: '22263' abstract: - lang: eng text: Recent studies at high redshift have revealed an enigmatic class of little red dots (LRDs) with extreme Balmer breaks, stronger than in any stellar atmosphere. However, it is unclear whether such objects exist at lower redshift, especially given the low number of LRDs reported at z ≲ 2. Here, we report the discovery of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.73, identified from JWST/NIRCam pure-parallel imaging taken by the PANORAMIC survey, and confirmed by deep VLT/X-Shooter spectroscopy. The rest-optical to near-infrared spectral energy distribution of PAN-BH*-1 is consistent with a photospheric continuum with effective temperature Teff ≈ 4800 K. The broad Hα emission line shows remarkably deep absorption, stronger than previously measured in any LRD. The absorption trough spans from −520 to +267 km s−1 with respect to the systemic redshift. The presence of blue- and red-shifted absorption suggests complex dynamics of the obscuring gas along the line of sight. We speculate that the absorption trough can be produced by a thick wind launched from a thick, rotating photospheric disk, the latter being the source of the red optical continuum. While the source is unresolved in the rest-optical JWST data (reff < 47 pc), the rest-near-UV Hubble Space Telescope imaging shows an extended morphology with (formular displayed) kpc, which we interpret as a host galaxy with a stellar mass of ∼10^8 M⊙, in line with the narrow Hα emission. The discovery of this object at cosmic noon highlights the feasibility of systematic searches for extreme LRDs with wide-area facilities such as Euclid and Roman. acknowledgement: "IOP Science home\r\nThe Astrophysical Journal Letters\r\nThe American Astronomical Society, find out more.\r\n\r\nThe following article isOpen access\r\nA Black Hole Star at Cosmic Noon: Extreme Balmer Break, Photospheric Continuum, and Broad Absorption by Thick Winds in a Little Red Dot at z = 1.7\r\nAlberto Torralba, Jorryt Matthee, Andrea Weibel, Rohan P. Naidu, Yilun Ma, Aidan P. Cloonan, Aayush Desai, Anna de Graaff, Jenny E. Greene, Christian Kragh JespersenShow full author list\r\n\r\nPublished 2026 June 30 • © 2026. The Author(s). Published by the American Astronomical Society.\r\nThe Astrophysical Journal Letters, Volume 1005, Number 2\r\nCitation Alberto Torralba et al 2026 ApJL 1005 L37\r\nDOI 10.3847/2041-8213/ae7bfd\r\n\r\nPDFOpens in a new tab.ePub\r\nAuthors\r\nFigures\r\nTables\r\nReferences\r\nArticle data\r\nPDFOpens in a new tab.ePub\r\nArticle metrics\r\n122 Total downloads\r\n\r\nShare this article\r\nArticle information\r\nAbstract\r\nRecent studies at high redshift have revealed an enigmatic class of little red dots (LRDs) with extreme Balmer breaks, stronger than in any stellar atmosphere. However, it is unclear whether such objects exist at lower redshift, especially given the low number of LRDs reported at z ≲ 2. Here, we report the discovery of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.73, identified from JWST/NIRCam pure-parallel imaging taken by the PANORAMIC survey, and confirmed by deep VLT/X-Shooter spectroscopy. The rest-optical to near-infrared spectral energy distribution of PAN-BH*-1 is consistent with a photospheric continuum with effective temperature Teff ≈ 4800 K. The broad Hα emission line shows remarkably deep absorption, stronger than previously measured in any LRD. The absorption trough spans from −520 to +267 km s−1 with respect to the systemic redshift. The presence of blue- and red-shifted absorption suggests complex dynamics of the obscuring gas along the line of sight. We speculate that the absorption trough can be produced by a thick wind launched from a thick, rotating photospheric disk, the latter being the source of the red optical continuum. While the source is unresolved in the rest-optical JWST data (reff < 47 pc), the rest-near-UV Hubble Space Telescope imaging shows an extended morphology with \r\n kpc, which we interpret as a host galaxy with a stellar mass of ∼108 M⊙, in line with the narrow Hα emission. The discovery of this object at cosmic noon highlights the feasibility of systematic searches for extreme LRDs with wide-area facilities such as Euclid and Roman.\r\n\r\nExport citation and abstract\r\nBibTeXRIS\r\n\r\nPrevious article in issue\r\nNext article in issue\r\n\r\nOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.\r\n\r\n1. Introduction\r\nThe unprecedented sensitivity of JWST has enabled the discovery of a new, abundant population of objects at redshifts z ≈ 3–9 nicknamed the “little red dots” (LRDs). These are characterized by their compact rest-frame optical morphology, broad emission lines, and a characteristic rest-UV to optical “V-shape” in their spectral energy distributions (SED; e.g., D. D. Kocevski et al. 2023; V. Kokorev et al. 2024; J. Matthee et al. 2024; I. Labbe et al. 2025).\r\n\r\nThe nature of LRDs is highly debated (see K. Inayoshi & L. C. Ho 2025, for a recent overview) as the LRDs show systematic differences with respect to other types of active galactic nuclei (AGN), such as faintness in X-rays (e.g., T. T. Ananna et al. 2024; M. Yue et al. 2024), mid-to-far-infrared dust emission (e.g., G. C. K. Leung et al. 2025; C. C. Williams et al. 2024; I. Delvecchio et al. 2025; D. J. Setton et al. 2025; M. Xiao et al. 2025), and radio (e.g., G. Mazzolari et al. 2026; M. A. Latif et al. 2025; K. Perger et al. 2025, see A. J. Gloudemans et al. 2025).\r\n\r\nA recurring spectral feature of LRDs is the presence of a strong Balmer break (e.g., D. J. Setton et al. 2025; B. Wang et al. 2024; R. E. Hviding et al. 2025; W. Q. Sun et al. 2026), in some cases stronger than any star or stellar population can produce. The two most prominent examples known to date are The Cliff at z ≈ 3.5 (A. de Graaff et al. 2025a) and MoM-BH* at z ≈ 7.8 (R. P. Naidu et al. 2025). The joint appearance of strong Balmer lines as well as strong Balmer breaks has been modeled as being due to absorption by a dense, neutral gas with a high column density in the line of sight to a highly ionizing source (K. Inayoshi & R. Maiolino 2025; X. Ji et al. 2025; A. Sneppen et al. 2026; A. Torralba et al. 2026). These observations have sparked the development of new theoretical models, ranging from a spherical envelope analogous to stellar atmospheres (e.g., M. C. Begelman & J. Dexter 2026; D. Kido et al. 2025; H. Liu et al. 2025; D. Nandal & A. Loeb 2026) or a thick accretion disk (e.g., H. Liu et al. 2025, 2026; K. Inayoshi et al. 2025; Y.-X. Chen et al. 2026).\r\n\r\nBesides their spectral features, the evolution of the LRD number densities is also in stark contrast to other types of AGNs (e.g., K. Inayoshi 2025). At 4 ≲ z ≲ 7, LRDs represent a few percent of the galaxy population (e.g., D. D. Kocevski et al. 2023, 2025; J. E. Greene et al. 2024; V. Kokorev et al. 2024; X. Lin et al. 2024; R. Maiolino et al. 2024; J. Matthee et al. 2024), with number densities of ≳10−5 Mpc−3. The number density does not appear to drop quickly beyond z > 5 (e.g., J. Zhang et al. 2026), with various LRDs having been confirmed at z > 8 (V. Kokorev et al. 2023; A. J. Taylor et al. 2025; R. Tripodi et al. 2025), well beyond the quasar redshift record (F. Wang et al. 2021). Photometric LRD candidates exist beyond z > 10 (T. S. Tanaka et al. 2025). In turn, the number density of LRDs seems to decline steeply at z < 4 (e.g., Y. Ma et al. 2026), with estimates of a number density of ∼10−6 cMpc−3 at z ∼ 2 and even ∼10−10 cMpc−3 at z ≈ 0.3 (X. Lin et al. 2026). While it is challenging to ensure a uniform selection function across such a large redshift baseline and dedicated spectroscopic follow-up of such lower redshift candidates has only just started, it is challenging to attribute five orders of magnitude to such effects.\r\n\r\nMotivated by the discovery of rare objects with extreme Balmer breaks at z > 3 and the very small number of known LRDs at lower redshift, we performed a dedicated search for extreme Balmer break objects using a template-match approach on a large compilation of JWST NIRCam data over ≈0.3 deg2 and z ≈ 1.5–7.0. This survey is presented in A. Weibel et al. (2026a). As part of an ongoing ground-based spectroscopic campaign of LRD candidates at z ∼ 2 (Y. Ma et al. 2026), we followed up the most luminous candidate with a photometric redshift of z ≈ 2 with the X-Shooter spectrograph on the Very Large Telescope (VLT). In this Letter, we present the discovery and spectroscopic confirmation of PAN-BH*-1, a luminous LRD at z = 1.73 with an extreme Balmer break comparable to the strongest observed in any LRD (and, in general, any astrophysical source). The low redshift of this source enables high-resolution spectroscopy from ground-based observatories that is otherwise impossible to obtain at high redshift.\r\n\r\nThroughout this Letter, we use a ΛCDM cosmology with Ωm = 0.31, ΩΛ = 0.69, and h = 0.677 as described by Planck Collaboration et al. (2020). All the magnitudes are given in the AB system (J. B. Oke & J. E. Gunn 1983).\r\n\r\n2. Observations\r\n2.1. Photometry and Source Selection\r\nWe identified PAN-BH*-1 (ID: PAN-1115, RA, DEC: 40.015835, −1.659363 J2000) as part of a systematic search across ≈0.3 deg2 of JWST NIRCam legacy imaging comprising at least six filters of coverage (A. Weibel et al. 2026b). Notably, this dataset includes the Cycle 1 pure parallel survey PANORAMIC (PID: 2514, PIs: Williams & Oesch; C. C. Williams et al. 2025) that contributes 28 of the 35 independent lines of sight, thereby enabling the discovery of rare objects such as PAN-BH*-1 across diverse large-scale structure environments. Specifically, this source was identified in the footprint j024000m0142 of the PANORAMIC DR1,15 which is adjacent to the A370 field (G. O. Abell et al. 1989), where archival images by the Hubble Space Telescope (HST) are available from the BUFFALO survey (C. L. Steinhardt et al. 2020). The HST/ACS images were processed with grizli and also released as part of the PANORAMIC dataset.\r\n\r\nPAN-BH*-1 is in the outskirts of the A370 lensing cluster, but the magnification is only μ ≈ 1.05 according to the models from A. Niemiec et al. (2023). Throughout the rest of the paper, we report the uncorrected flux measurements, since the effect of magnification (∼5%) is negligible given the uncertainties in the observations and the lensing model.\r\n\r\nThe search strategy and full photometric selection are described in a companion paper (A. Weibel et al. 2026a). Briefly, that work presents a new selection of LRDs as a combination of a “black hole star” template (BH*; R. P. Naidu et al. 2025) embedded in a host galaxy, instead of the typically used “V-shaped” selections (e.g., D. D. Kocevski et al. 2025; V. Kokorev et al. 2024). The host galaxies are modeled using eazy’s blue_sfhz templates. The BH*s are modeled using a novel template set comprising empirical luminosity-based stacks constructed in W. Q. Sun et al. (2026), the cloudy template from R. P. Naidu et al. (2025), and by using spectra of prominent LRDs spanning the observed effective temperature range (I. Labbe et al. 2024; A. de Graaff et al. 2025a; B. Wang et al. 2026).\r\n\r\nPAN-BH*-1 stood out as one of the few sources where the BH* template effectively dominated all the light over the full wavelength range covered by NIRCam (hence the name). The redshift of PAN-BH*-1 was estimated to be zphot = 1.85. Follow-up VLT/X-Shooter spectroscopy confirmed the redshift as zspec = 1.731 (see Section 3.2).\r\n\r\nPAN-BH*-1 is also covered by archival data from the VLT with the HAWK-I camera in the Ks band (G. B. Brammer et al. 2016) and in data from the Spitzer Space Telescope in IRAC bands 1 and 3 (3.6 and 5.7 μm), and MIPS 24 μm (P. Capak 2019). PAN-BH*-1 is detected in the Ks band and in the two IRAC filters. Performing Spitzer photometry of this source is challenging due to the large point spread function (PSF) and a neighboring source, especially in the MIPS band. However, the NIRCam photometry of the neighboring source suggests it has a limited contribution to the IRAC fluxes. The details of the photometry extraction are described in Appendix A, and the measured magnitudes in Table 2.\r\n\r\n2.2. VLT/X-Shooter Spectroscopy\r\nPAN-BH*-1 was observed for 5.8 ks with the X-Shooter spectrograph (J. Vernet et al. 2011) on the VLT as a bright backup target for program 116.294D (PI: Matthee) in visitor mode on 2025 December 17. The main aim of this program was to confirm candidate LRDs at cosmic noon (Y. Ma et al. 2026). These observations confirmed the redshift through the detection of Hα at z = 1.731. A DDT program (ID 116.2AQ0; PI: Matthee) obtained additional follow-up data of PAN-BH*-1 in service mode for 26.2 ks during 2026 January 10–26, yielding a total exposure time of 8.9 hr. X-Shooter observes with three arms simultaneously, UVB, VIS, and near-infrared (NIR), covering rest-frame wavelengths of ≈0.14–0.9 μm, albeit hampered by skyline emission and telluric absorption, primarily in the rest-frame optical.\r\n\r\nThe observing conditions were clear, with a seeing ranging from 05 to 07 (median 06). The service mode observations were primarily conducted during dark nights, with some gray (FLI = 0.03–0.6, median 0.1), and a typical airmass of 1.35. We used UVB, VIS, and NIR slits with widths 10, 09, and 09, yielding a nominal resolution of R = 5400, 8900, and 5600, respectively (FWHM ∼53 km s−1 for NIR). The target acquisition was done using blind offsets from a reference star, due to the target being too faint for direct acquisition. We used a standard nodding on the slit pattern, with 4″ nod throws in an ABBA pattern, and 1″ jitters in the NIR arm to improve the sky subtraction. In each observing block of ≈1 hr, the exposure times were 700, 655, and (2×)365 s for the three arms at each nod position.\r\n\r\nThe reduction of the X-Shooter data uses a combination of EsoRex libraries16 and Python code based on the reduction pipeline employed in J. Matthee et al. (2021). Each observing block was reduced separately. We used standard stars taken during the observing night for a first-pass flux calibration. Telluric corrections were applied using the molecfit tool (A. Smette et al. 2015) implemented in the X-Shooter EsoRex pipeline. Telluric stars were observed during the visitor nights, but they were not always observed during the service mode observations in January. For those observations, we took the telluric star that was observed at the closest observing date. Based on the variation in telluric absorption among the reference stars taken during this period, we estimate the variation in the transmission and propagate the uncertainty in the telluric correction. For each observing block, we then extracted an optimally extracted 1D spectrum using the spatial profile of the Hα line, thus accounting for seeing variations and (more importantly) minor errors in the accuracy of the slit pointing. Before median combining these spectra, we normalize them by the median Hα flux of all observations to account for variations in slit losses and flux calibrations.\r\n\r\nBesides Hα (integrated S/N = 75) and Hβ (integrated S/N = 6; Section 3.2), we also detect continuum emission in the best regions in the H and K bands at 1.6 μm and 2.1 μm, respectively, with a low signal-to-noise ratio (S/N) of ∼1 per resolution element. Unfortunately, the [O iii] λλ4960, 5008 doublet is undetectable because the observed wavelengths are impacted by very strong telluric absorption. No other lines or continuum are detected in the X-Shooter spectrum.\r\n\r\n3. Properties of PAN-BH*-1\r\n3.1. Spectral Shape: A Photospheric Continuum with Strong Hα Emission\r\nThe photometric SED of PAN-BH*-1 has remarkable similarities with The Cliff (Figure 1): luminous in the rest optical, with a sudden drop toward the rest-UV around the Balmer limit, and very weak near-to-mid infrared continuum emission. With a rough extrapolation of the two HST photometric points using a power-law fit (fλ ∝ λβ), we obtain a UV slope of β = −0.1 ± 1.2, and MUV = −16.7 ± 0.7. For the rest-frame optical to NIR data, we fit a Planck blackbody law to the JWST data points, after subtracting the measured Hα flux (see Section 3.2) from the F200W photometry. The rest-optical and NIR photometry of PAN-BH*-1 is remarkably well described by a single temperature blackbody with T = 4204 K (with a best-fit ). We measure the strength of the Balmer break from the fν ratio F115W/F814W = 7 ± 1, in line with the Balmer break strengths of The Cliff (; A. de Graaff et al. 2025a)17 and MoM-BH* (7.8 ± 1.8; R. P. Naidu et al. 2025), measured from JWST/NIRSpec PRISM spectra as fν,4000–4100/fν,3620−3720. In Figure 2, we compare the Balmer break strength with the spectroscopic sample of A. de Graaff et al. (2025b), showing that out of 134 sources, only two have breaks significantly above 5. This suggests that PAN-BH*-1 has among the most extreme Balmer breaks known, although we caution that our value is derived from wide-band photometry with pivot wavelengths corresponding to 4212 and 3042 Å, respectively, rather than from spectroscopy.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 1. SED of PAN-BH*-1 Top: cutouts from all the HST and JWST images in which PAN-BH*-1 is covered. It shows a remarkably compact morphology in all the wavelengths, resolved only in the HST F606W and F814W bands (Section 3.3). Bottom: photometry from JWST/NIRCam (blue squares), HST/ACS (purple pentagons), and Spitzer/IRAC+MIPS (red hexagons, and red triangle for the 5σ upper limit). The empty square is the F200W flux after subtracting the Hα flux measured from X-Shooter spectroscopy. We show the spectrum of The Cliff for comparison (gray line), shifted to z = 1.73 and normalized to the F150W flux of PAN-BH*-1. We also show the best-fitting blackbody spectrum (blue dashed line) and the best model from the synthetic LRD atmosphere models from H. Liu et al. (2026), shifted to z = 1.73 (green line), undersampled by a factor of 500 for clarity.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\nZoom InZoom OutReset image size\r\nFigure 2. Spectroscopic sample of LRDs by redshift and Balmer break strength. We plot the redshift and Balmer break strength of PAN-BH*-1, and the JWST sample from A. de Graaff et al. (2025b) (purple diamonds), and three local LRDs in X. Lin et al. (2026), for comparison. We also highlight three sources with a particularly strong Balmer break: The Cliff (A. de Graaff et al. 2025a), MoM-BH* (R. P. Naidu et al. 2025), and CAPERS-LRDz9 (A. J. Taylor et al. 2025). The Balmer break strength of the JWST spectroscopic sample is computed as fν,4000–4100/fν,3620–3720, whereas the value for PAN-BH*-1 is directly obtained from the F115W/F814W photometry.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\n3.2. Hα and Hβ Emission Lines\r\nThe Hα profile appears as a complex combination of a broad line with strong absorption close to the systemic redshift. We fit the Hα emission line with a similar model as the one used in A. Torralba et al. (2026) and J. Matthee et al. (2026). The Hα model consists of two Gaussian emission components (with narrow and intermediate line widths), and a broad symmetric exponential convolved with the intermediate profile and parameterized as in F. D’Eugenio et al. (2025a). The absorption is implemented as an opacity law defined as e−τ(λ), where τ(λ) also follows a single Gaussian velocity distribution (F. D’Eugenio et al. 2025a, 2025b; A. Torralba et al. 2026). For simplicity, we assume a covering factor of Cf = 1 for the absorbing gas. In previous works, the width of the narrow component is tied to that of [O iii], assuming both components come from the same region, often interpreted as the interstellar medium (ISM) of the host galaxy. In this case, we have no information about [O iii] due to this doublet falling in a wavelength range heavily affected by strong telluric absorption. We fit the Hα line after masking relevant skylines and strong telluric absorption bands. The fitted Hα parameters are listed in Table 1 and the best-fit model is shown in Figure 3. The absorption feature is notably strong, with an equivalent width of EWabs = −148 ± 12 Å with respect to the fitted continuum and 12.2 ± 0.2 Å if including the broad emission component. The absorption corresponds to a Balmer optical depth at the line center of , reaching roughly the continuum level. The FWHM of the single Gaussian fitted to the absorber is 283 ± \ 8 km s−1, and is offset from the systemic redshift by −94 ± 4 km s−1. We note that this parameterization is somewhat arbitrary, and we discuss in detail the absorber properties in Section 4.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 3. Hα spectrum, and the best fit to our fiducial model. We show the X-Shooter R ∼ 5600 spectrum of the Hα line of PAN-BH*-1, along with the best-fit to the model described in Section 3.2; total model (red solid line) and individual components (discontinuous color lines). The red wing of the line is severely affected by telluric absorption, thus the large uncertainties.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\nTable 1. Properties of PAN-BH*-1\r\n\r\nParameter\tValue\tUnit\r\nWidth (FWHM; Hα)\r\nExponential\t1257 ± 27\tkm s−1\r\nIntermediate\t687 ± 43\tkm s−1\r\nNarrow\t184 ± 12\tkm s−1\r\nAbsorption\t283 ± 8\tkm s−1\r\nFlux (Hα)\r\nExponential\t643 ± 7\t10−18 erg s−1 cm−2\r\nIntermediate\t19 ± 5\t10−18 erg s−1 cm−2\r\nNarrow\t38 ± 3\t10−18 erg s−1 cm−2\r\nTotal\t522 ± 7\t10−18 erg s−1 cm−2\r\nGeneral properties\r\n(LHα/erg s−1)\t43.046 ± 0.006\t⋯\r\nEW0(Hα)\t520 ± 20\tÅ\r\nSFR(Hα, narrow)a\t2.1 ± 0.2\tM⊙ yr−1\r\nSFR(Hα, narrow)b\t3.3 ± 0.3\tM⊙ yr−1\r\nreff,UV (F606W+F814W)\t\tkpc\r\nreff,opt (F200W)\t<0.047\tkpc\r\nHα/Hβ (total)\t>9.4\t⋯\r\nHα/Hβ (narrow)\t5 ± 1\t⋯\r\nNotes. aCalibration from I. G. Kramarenko et al. (2026). bCalibration from R. C. Kennicutt & N. J. Evans (2012). SFR values calculated assuming no dust attenuation.\r\n\r\nDownload table as: \r\nASCIITypeset image\r\n\r\nThe Hβ line is marginally detected. After undersampling the spectrum by a factor 5, a hint of a weak narrow component can be identified (Figure 4), along with a tentative absorption at the same mean velocity as in Hα. We fit the best Hα model to the Hβ spectrum, only rescaling it by a multiplicative factor, and adding a flat continuum component. By doing this, we find an Hβ flux of (47 ± 8) × 10−18 erg s−1 cm−2 (S/N ≈ 6). Conservatively, we obtain a Balmer decrement of Hα/Hβ > 9.4 (at a 3σ confidence level), in line with the high decrements found for the LRD population (e.g., G. P. Nikopoulos et al. 2026; A. de Graaff et al. 2025b; J. Matthee et al. 2026). In Figure 5, we show the Hβ spectrum compared to the rescaled Hα model. By matching the best-fit Hα profile with the data at the expected observed wavelength for Hβ (±5000 km s−1), we obtain a better agreement (, BIC = 1537) than fitting a flat continuum only (, BIC = 1658) with ΔBIC = 121 ≫ 10, strongly favoring a detection of a broad Hβ emission line, and securing the spectroscopic redshift. Similarly, we fit a narrow Gaussian to Hβ with the same width and velocity as the Hα best-fit model, assuming a completely saturated absorption. We obtain a Balmer decrement for the narrow component of Hα/Hβ = 5 ± 1, which would imply a dust extinction of using a J. A. Cardelli et al. (1989) attenuation law, under the assumption of case B recombination. However, due to the low S/N of Hβ this result is only tentative, and compatible with a standard Case B value within ∼2σ.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 4. X-Shooter spectrum of Hα and Hβ of PAN-BH*-1 (blue). We compare to the spectrum of The Cliff (gray; data from JWST DDT #9433), normalized in each panel to the flux of PAN-BH*-1 in the range v ∈ (−3000, −2000) km s−1. Due to the low S/N, the Hβ spectrum of PAN-BH*-1 is rebinned to a coarser grid by a factor 5, after masking the most relevant skylines.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\nZoom InZoom OutReset image size\r\nFigure 5. Hβ spectrum. The spectrum is rebinned by a factor of 10 with inverse variance flux weighting for visual clarity, due to the low S/N. We compare to the best-fit Hα model, scaled by a factor of 0.112. In the bottom panel, we show the χ residuals between the spectrum and the rescaled Hα model in black, and for only the continuum in pink (ΔBIC = 121 strongly favoring the presence of a broad Hβ line).\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\n3.3. Spatial Morphology\r\nIn order to assess whether PAN-BH*-1 is spatially resolved, we use the Bayesian profile fitting software pysersic (I. Pasha & T. B. Miller 2023)18 to fit a single Sérsic profile to the JWST and HST imaging data of PAN-BH*-1. For JWST/NIRCam, we choose F200W as the filter with the highest S/N in the short wavelength channel, benefiting from a high spatial resolution and probing rest-frame optical wavelengths. To model its PSF, we use version 2.2.0 of the stpsf software (formerly webbpsf, M. D. Perrin et al. 2014). For the two HST bands F606W and F814W, we instead construct empirical PSFs from public imaging data in the GOODS-S field following A. Weibel et al. (2024). In all three bands, we sample the posterior with the No U-turn sampler in two chains with 1000 warm-up and 2000 sampling steps each. We find that PAN-BH*-1 is unresolved with NIRCam in F200W where the effective radius converges toward the edge of the prior at 0.25 pixels. Using the 95th percentile of the posterior chains as an upper limit on the effective radius, we find a rest-optical size of reff < 47 pc.\r\n\r\nPAN-BH*-1 appears to be resolved in the HST images corresponding to rest-frame pivot 0.2 and 0.3 μm, respectively. Due to the low signal-to-noise of the F606W and F814W photometry, we fit both bands simultaneously fixing all the morphological parameters in both images. We measure physical effective radii of kpc (see Appendix B). The modest stretching by the foreground A370 lensing cluster could imply a correction of ∼10% to the measured radius (A. Niemiec et al. 2023), which we disregard given the uncertainties. These measured sizes are consistent with the typical sizes for galaxies with a stellar mass ≲ 109 M⊙ at z = 1.75 (A. van der Wel et al. 2014). These findings are consistent with the scenario of a compact LRD “engine” dominating the rest-optical light embedded in a host galaxy, whose contribution becomes significant blueward of the Balmer break (see A. P. Cloonan et al. 2026, for a relevant discussion).\r\n\r\n4. Absorber Kinematics\r\nAs described in Section 3.2, the velocity distribution of the absorber is empirically modeled with a Gaussian, which we find has a central velocity of −94 ± 4 km s−1 relative to the redshift of the narrow emission component (adopted as systemic). The absorption trough extends from negative to positive velocities with respect to the redshift of the narrow component, but also with respect to the center of the symmetric exponential wings. However, there are several degeneracies between the shape of the absorber and other components of the emission line, such as the narrow central emission (see Section 3.2). Furthermore, direct interpretation of the absorber center velocity shift is challenging in an optically thick gas with presumably complex dynamics, and it does not necessarily trace bulk motion. A more robust, physically motivated pair of quantities is the minimum and maximum absorber velocities. We define them as the values where the transmission of the Balmer absorber increases to 99%, km s−1 and km s−1. These values trace the largest velocities in the line of sight of gas with significant Balmer absorption. The absorbing trough extends over 787 ± 17 km s−1 under this definition. The values of and are relatively agnostic to the choice of the shape of the absorber, since they are determined by the wavelength where the line profile deviates from a broad, symmetric exponential profile. In Figure 6, we illustrate three proposed configurations of the velocity distribution of the absorbing gas that could explain the shape of the observed Balmer absorption, and we discuss these scenarios below.\r\n\r\nZoom InZoom OutReset image size\r\nFigure 6. Geometric configurations for the absorber. We illustrate three scenarios that could give rise to the observed Balmer absorption in PAN-BH*-1. In scenario (a), the obscuring agent is a thick screen of gas with a certain bulk velocity, and turbulent motions produce the broadening of the absorption trough. In (b), there are two (or more) absorbers with opposite velocities in the line of sight. These first two scenarios are dynamically unstable; therefore, variability is expected in the absorption. Lastly, in (c), we observed an extended source through a disk wind with a rotational component (vϕ) in addition to the poloidal (nonazimuthal) velocity (vp). In the last scenario, the redshifted absorption is produced by streamlines that oppose the observer when projected along the line of sight, despite the fact that the gas is outflowing from the central source.\r\n\r\nDownload figure:\r\n\r\nStandard imageHigh-resolution image\r\n4.1. Unstable Gas Flows?\r\nThe fact that there is significant absorption at both negative and positive velocities with respect to the systemic redshift cannot be simply explained by an axisymmetric outflowing or inflowing wind. In the case of observing a compact object through a spherically symmetric, nonturbulent bulk flow, a classical P Cygni profile is expected, with a purely blueshifted absorption (or redshifted if the wind is infalling). The fact that we also see redshifted absorption rules out this simple scenario. In principle, turbulent motions could also produce broadening of the absorbing medium (scenario a in Figure 6). However, the required turbulent velocity dispersion σturb ≈ 120 km s−1 (from the Gaussian fit in Section 3.2) is comparable to the mean velocity of the absorption trough, meaning that turbulence dominates the gas flow. In such a case, strong variability of the absorption profile would be expected, given the typical dynamical crossing times (see Sect. 4.1 in F. D’Eugenio et al. 2025b). For example, for a radius of 1016 cm (e.g., A. Torralba et al. 2026) and a mass of 106 M⊙, the dynamical freefall time is yr. Moreover, the turbulent velocity would be highly supersonic, and the dissipation timescale would be comparable to the dynamical time (e.g., M.-M. Mac Low 1999). Alternatively, in the context of a strong Balmer absorber at z ∼ 7, F. D’Eugenio et al. (2026) recently discussed a “breathing mode” scenario with cyclic inflows and outflows along the same line of sight, with the gas being in different phases at different depths (scenario b in Figure 6; see also K. Park et al. 2017). In this case, the same arguments regarding the stability of the absorber would apply, and absorber variability is expected on observed timescales of ∼5 yr (for a source at z = 1.7), which is testable with future observations.\r\n\r\n4.2. The Case for the Disk Wind Hypothesis\r\nAn alternative, dynamically stable scenario is a disk wind configuration (scenario c in Figure 6). Here, the wind would be launched from a thick disk near the central engine, which we speculate could be the source of the optical continuum emission (e.g., H. Liu et al. 2025, 2026; L. Zwick et al. 2025; Y.-X. Chen et al. 2026). A rotating disk would imprint to the wind an azimuthal velocity component (vϕ). Observations at specific lines of sight, particularly for high inclination angles (close to edge-on) where the rotational component dominates the poloidal velocity, can give rise to both blueshifted and redshifted absorption features (D. Proga et al. 2000; P. B. Hall et al. 2002, 2013; D. Proga & T. R. Kallman 2004; M. Giustini & D. Proga 2012). Most observed LRDs have blueshifted P Cygni–like absorbers (J. Matthee et al. 2026), which can be naively interpreted as a uniformly expanding shell. The low incidence of redshifted Balmer absorbers in LRD spectra (e.g., I. Labbe et al. 2024; A. de Graaff et al. 2025a; F. D’Eugenio et al. 2025b, 2026; Y. Ma et al. 2026) can therefore be explained by the requirement of high inclination angles to observe such features (see also A. Sneppen et al. 2026). Such a picture is broadly in line with disk wind models for AGN with broad absorption lines (e.g., P. B. Hall et al. 2002; H. Zhou et al. 2019) and around stars with circumstellar disks (e.g., J. Erkal et al. 2022), such as accreting T Tauri stars (S. Edwards et al. 2006) or cataclysmic variables (D. Proga 2003).\r\n\r\n4.3. Implications of Rotating Winds for the Emission Lines of LRDs\r\nThe disk wind hypothesis would imply that a photosphere in the shape of a rotating disk is the source of the optical continuum emission, and drives winds that can explain the observed absorption trough. Emission lines originating in a thin rotating disk would have a double-peaked profile in the idealized case (for most inclination angles), but this is not necessarily true if the disk is not sufficiently thin (e.g., N. Murray & J. Chiang 1997), for instance, in the case of a puffed-up disk associated with super-Eddington accretion (e.g., H. Liu et al. 2026). In addition, most line emission would not be produced directly at the base of the disk, but slightly outside (e.g., via collisional cooling or residual recombination; A. Torralba et al. 2026), where the rotational velocity is lower, and the dynamics are complex (e.g., G. A. Shields 1977).\r\n\r\nThe Balmer lines of most LRDs are dominated by broad, symmetric exponential components that are associated with broadening by electron scattering (e.g., V. Rusakov et al. 2026; J. Matthee et al. 2026). For PAN-BH*-1, the Hα line profile of PAN-BH*-1 is compatible with a broad exponential profile emerging through a dense wind where the absorption trough is produced. In dense gas with a large column density of neutral hydrogen, and optically thick to Balmer transitions (NHI,2s ≳ 1014 cm−2), resonant scattering effects become important. Crucially, resonant scattering impacts Hα and Hβ differently (e.g., S.-J. Chang et al. 2026), hence the 3D radiative transfer and photon redistribution of both lines may produce different profiles (see, e.g., Figure 2 in D. Proga 2003). Therefore, the empirical fitting and interpretation of the absorption profiles becomes nontrivial. Dedicated radiative transfer modeling is necessary to study such effects, and they can be tested in other emission lines with high optical depth, such as He i λ10830 Å, or resonant lines like C iv λ1550.\r\n\r\n5. Implications for the Galaxy and Black Hole Masses\r\n5.1. Properties of the Host Galaxy\r\nAssuming that the narrow component of Hα corresponds to ISM emission in the host galaxy, we compute the associated star formation rate using the local calibration from R. C. Kennicutt & N. J. Evans (2012) and assuming no dust attenuation. We obtain SFR(Hα) = 3.3 ± 0.3 M⊙ yr−1. A somewhat lower value of SFR(Hα) = 2.1 ± 0.2 M⊙ yr−1 is obtained using the high-redshift (z ≳ 4) calibrations in I. G. Kramarenko et al. (2026), which might be more appropriate for a young dwarf galaxy with a bursty star formation history. The star formation rates are low, but in line with a main-sequence galaxy with (extrapolating the relation from J. S. Speagle et al. 2014). Assuming zero dust attenuation, the UV absolute magnitude (MUV = −16.7 ± 0.7; Section 3.1) would imply SFR(UV) = 0.18 ± 0.12 M⊙ yr−1 (R. C. Kennicutt & N. J. Evans 2012). The discrepancy between the UV and Hα inferred star formation rate suggests there is some amount of dust attenuation in the host galaxy.\r\n\r\nWe derive a dynamical mass from the width of the narrow component Hα line and the estimated UV size as , adopting the empirical virial correction K(n)K(q) from A. van der Wel et al. (2022), where K(n) and K(q) are functions of the best-fit ellipticity and Sérsic index (see Appendix B). Adopting a Mdyn/M* factor of 40 as found by A. de Graaff et al. (2024) for dwarf galaxies at high redshift, we infer a stellar mass of . However, the Mdyn/M* is very uncertain in this regime, and the uncertainty can span over 1 dex (A. Saldana-Lopez et al. 2025). We advise caution in interpreting this result, as there are large uncertainties in the measurements of the narrow Hα component, the HST morphology, and the empirical relations used.\r\n\r\nAs discussed in Section 4, the absorption profile is compatible with broadening by a rotating disk wind, and numerical modeling of such configurations often predicts a narrow component arising from increased transmission due to purely kinematic effects in the wind geometry (D. Proga et al. 2000; D. Proga 2003; D. Proga & T. R. Kallman 2004). This would be an alternative explanation for at least part of the narrow component flux. On the other hand, most LRDs present narrow [O iii] emission that is often associated with the host galaxy. Indeed, the ionized gas producing [O iii] emission should have associated emission in the Hα and higher-order Balmer lines. However, constraining this component largely depends on the assumptions on dust attenuation or ISM conditions, and requires very high S/N and resolution data. Deep, space-based follow-up observations of PAN-BH*-1 would be very constraining for the wind kinematics (e.g., by the joint analysis of Hβ) and to assess whether a narrow component comes from a host galaxy (e.g., by comparing to a narrow Hβ component or [O iii] λλ4960, 5008).\r\n\r\n5.2. Black Hole Mass From Photosphere Models\r\nThe general physical setup of LRDs is an open debate, and their masses are a major unknown. Due to the multiple differences with respect to the classical AGN population, the validity of standard virial calibrations has been questioned (e.g., V. Rusakov et al. 2026; J. E. Greene et al. 2026; A. Sneppen et al. 2026; A. Torralba et al. 2026, although see, e.g., M. Brazzini et al. 2025, 2026; J. Scholtz et al. 2026 for an alternative interpretation).\r\n\r\nOne can obtain a mass estimate assuming a system in radiative equilibrium with Lbol/LEdd = 1 (e.g., H. Umeda et al. 2026); this yields a total mass of ≈106 M⊙, using the bolometric luminosity from integrating the best-fit blackbody in Section 3.1. Recently, H. Liu et al. (2026) developed a synthetic spectral library of LRD atmosphere models. In these models, the density of the photosphere is regulated by the net surface gravity of an optically thick atmosphere, enabling constraints on the mass of the system. We fit the JWST photometry of PAN-BH*-1 using the models from H. Liu et al. (2026), assuming a negligible contribution from a host galaxy to the optical continuum. The best-fit model has effective temperature Teff = 4800 K, surface gravity , and metallicity (; see Figure 1). The best-fit implies a total mass of the system (BH plus gas) of (Equation (6) in H. Liu et al. 2026, assuming hydrostatic equilibrium). For the second and third best fits, we obtain and −2, respectively (, respectively; with the same metallicity and effective temperature), which would imply lower limits to the system mass between and 4. The bolometric luminosity of PAN-BH*-1 (from the integral of the best-fit green curve in Figure 1) implies an Eddington luminosity ratio of L/LEdd ≲ 13, assuming the best-fit mass from the H. Liu et al. (2026) models. The elevated Eddington ratio is in line with the hypothesis of a radiation-driven wind discussed in Section 4, and allows for somewhat larger system masses. The low masses obtained with this model, combined with the stellar mass inferred from dynamical arguments for the host galaxy (Section 3.3) set lower limits to the BH-to-stellar mass ratio of MBH/M* ≳ 10−4–10−2, which are compatible with the relations observed in the Local Universe, within the large uncertainties (A. E. Reines & M. Volonteri 2015).\r\n\r\n6. Conclusions\r\nIn this Letter, we presented the discovery and spectroscopic confirmation of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.731. The strength of the Balmer break (F115W/F814W = 7 ± 1) is comparable to the most extreme LRDs known, The Cliff (A. de Graaff et al. 2025a) and MoM-BH* (R. P. Naidu et al. 2025). We summarize the observations and our main conclusions as follows.\r\n\r\n\r\n1. \ \r\nWe obtained deep VLT/X-Shooter spectroscopy of PAN-BH*-1. The Hα emission line is luminous and broad (LHα = 1043 erg s−1), and has an unusually strong absorption. Hβ is detected with an S/N ≈ 6, and we conservatively estimate a lower limit for the Balmer decrement of Hα/Hβ > 9.4 (at a 3σ confidence level), in line with other LRDs in the literature (e.g., A. de Graaff et al. 2025b; G. P. Nikopoulos et al. 2026).\r\n2. \r\nThe absorption trough spans from −520 to 267 km s−1 (at a transmission level of 99%). We interpret the presence of blue- and redshifted absorption as produced by a disk wind, analogous to those analyzed in the context of broad absorption line quasars or accreting stars. This hypothesis would imply that the source of the optical continuum is likely a thick photospheric disk.\r\n3. \r\nWe detect a narrow Hα component (FWHM = 184 ± 12 km s−1), which we interpret as probing a host galaxy with M* ≈ 108 M⊙ and SFR = 2–3 M⊙. This interpretation is in line with the extended rest-NUV morphology measured in the HST bands (\r\n kpc).\r\n4. \r\nBy fitting the synthetic atmosphere models of H. Liu et al. (2026), we estimate a system mass (BH+envelope) of 104–106 M⊙. The inferred masses, together with the stellar mass inferred from morphology and narrow emission line dynamics, imply BH-to-stellar mass ratios of 10−2–10−4, close to the extrapolated trend in the local Universe (A. E. Reines & M. Volonteri 2015).\r\n5. \r\nThe confirmation of this source at cosmic noon (magnitude of ≈22 in the K band, Hα flux ≈5 × 10−16 erg s−1 cm−2) proves the feasibility of detecting extreme LRDs at such epochs with wide-area spectroscopic surveys like Euclid or the forthcoming Nancy Grace Roman Space Telescope.\r\n\r\nAcknowledgments\r\nA.T. thanks Debasish Dutta and Tamara Bogdanović for useful conversations about stellar and AGN winds.\r\n\r\nWe thank the scientific referee for the useful and constructive feedback, which helped improve the quality of this paper.\r\n\r\nJ.M. and A.T. acknowledge funding by the European Union (ERC, AGENTS, 101076224). The work of CCW is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. A.P.C. warmly acknowledges the support of the National Science Foundation through the NSF Graduate Research Fellowship Program. A.d.G. acknowledges support from a Clay Fellowship awarded by the Smithsonian Astrophysical Observatory.\r\n\r\nBased on observations made with ESO Telescopes at the Paranal Observatory under program IDs 116.294D and 116.2AQ0.\r\n\r\nThis work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs #2514 and #9433. C.C.W. gratefully acknowledges support for program JWST-GO-2514 provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. The authors acknowledge the team led by co-PIs R. Maiolino and F. D’Eugenio for developing their observing program with a zero-exclusive-access period.\r\n\r\nThis research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with program #15117.\r\n\r\nThe JWST and HST data presented in this article were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via doi:10.17909/ydwx-st06.\r\n\r\nThis work is based in part on observations made with the Spitzer Space Telescope, which was operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The Spitzer data used in this work can be found in doi:10.26131/IRSA3.\r\n\r\nThis work was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #25-659 “Little Red Dots, Big Open Questions.”\r\n\r\nJWST cartoon in Figure 6, credit: NASA.\r\n\r\nFacilities: VLT:Kueyen - Very Large Telescope (Kueyen) (X-Shooter), VLT:Yepun (HAWK-I), JWST - James Webb Space Telescope (NIRCam, NIRspec), HST - Hubble Space Telescope satellite (ACS), Spitzer - Spitzer Space Telescope satellite (IRAC, MIPS) - .\r\n\r\nSoftware: astropy (Astropy Collaboration et al. 2013, 2018; Astropy Collaboration et al. 2022), NumPy (C. R. Harris et al. 2020), SciPy (P. Virtanen et al. 2020), pysersic (I. Pasha & T. B. Miller 2023), stpsf (M. D. Perrin et al. 2014), lmfit (M. Newville et al. 2014), EsoRex (ESO CPL Development Team 2015), Claude (used for Python coding; https://claude.ai/), SEP (K. Barbary 2016)." article_number: L37 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Alberto full_name: Torralba Torregrosa, Alberto id: 018f0249-0e87-11f0-b167-cbce08fbd541 last_name: Torralba Torregrosa orcid: 0000-0001-5586-6950 - first_name: Jorryt J full_name: Matthee, Jorryt J id: 7439a258-f3c0-11ec-9501-9df22fe06720 last_name: Matthee orcid: 0000-0003-2871-127X - first_name: Andrea full_name: Weibel, Andrea last_name: Weibel - first_name: Rohan P. full_name: Naidu, Rohan P. last_name: Naidu - first_name: Yilun full_name: Ma, Yilun last_name: Ma - first_name: Aidan P. full_name: Cloonan, Aidan P. last_name: Cloonan - first_name: Aayush A full_name: Desai, Aayush A id: 502cfd30-32c1-11ee-a9a4-d8dad5c6739e last_name: Desai - first_name: Anna full_name: De Graaff, Anna last_name: De Graaff - first_name: Jenny E. full_name: Greene, Jenny E. last_name: Greene - first_name: Christian Kragh full_name: Jespersen, Christian Kragh last_name: Jespersen - first_name: Ivan full_name: Kramarenko, Ivan id: 9a9394cb-3200-11ee-973b-f5ba2a8b16e4 last_name: Kramarenko orcid: 0000-0001-5346-6048 - first_name: Sara full_name: Mascia, Sara id: edaf889c-c7cd-11ef-ab1b-bb28c431bd29 last_name: Mascia - first_name: Pascal A. full_name: Oesch, Pascal A. last_name: Oesch - first_name: Wendy Q. full_name: Sun, Wendy Q. last_name: Sun - first_name: Christina C. full_name: Williams, Christina C. last_name: Williams citation: ama: 'Torralba Torregrosa A, Matthee JJ, Weibel A, et al. A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. The Astrophysical Journal Letters. 2026;1005(2). doi:10.3847/2041-8213/ae7bfd' apa: 'Torralba Torregrosa, A., Matthee, J. J., Weibel, A., Naidu, R. P., Ma, Y., Cloonan, A. P., … Williams, C. C. (2026). A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. The Astrophysical Journal Letters. IOP Publishing. https://doi.org/10.3847/2041-8213/ae7bfd' chicago: 'Torralba Torregrosa, Alberto, Jorryt J Matthee, Andrea Weibel, Rohan P. Naidu, Yilun Ma, Aidan P. Cloonan, Aayush A Desai, et al. “A Black Hole Star at Cosmic Noon: Extreme Balmer Break, Photospheric Continuum, and Broad Absorption by Thick Winds in a Little Red Dot at z = 1.7.” The Astrophysical Journal Letters. IOP Publishing, 2026. https://doi.org/10.3847/2041-8213/ae7bfd.' ieee: 'A. Torralba Torregrosa et al., “A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7,” The Astrophysical Journal Letters, vol. 1005, no. 2. IOP Publishing, 2026.' ista: 'Torralba Torregrosa A, Matthee JJ, Weibel A, Naidu RP, Ma Y, Cloonan AP, Desai AA, De Graaff A, Greene JE, Jespersen CK, Kramarenko I, Mascia S, Oesch PA, Sun WQ, Williams CC. 2026. A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. The Astrophysical Journal Letters. 1005(2), L37.' mla: 'Torralba Torregrosa, Alberto, et al. “A Black Hole Star at Cosmic Noon: Extreme Balmer Break, Photospheric Continuum, and Broad Absorption by Thick Winds in a Little Red Dot at z = 1.7.” The Astrophysical Journal Letters, vol. 1005, no. 2, L37, IOP Publishing, 2026, doi:10.3847/2041-8213/ae7bfd.' short: A. Torralba Torregrosa, J.J. Matthee, A. Weibel, R.P. Naidu, Y. Ma, A.P. Cloonan, A.A. Desai, A. De Graaff, J.E. Greene, C.K. Jespersen, I. Kramarenko, S. Mascia, P.A. Oesch, W.Q. Sun, C.C. Williams, The Astrophysical Journal Letters 1005 (2026). corr_author: '1' das_tickbox: '1' dataavailabilitystatement: "Based on observations made with ESO Telescopes at the Paranal Observatory under program IDs 116.294D and 116.2AQ0.\r\n\r\nThis work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs #2514 and #9433. C.C.W. gratefully acknowledges support for program JWST-GO-2514 provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. The authors acknowledge the team led by co-PIs R. Maiolino and F. D’Eugenio for developing their observing program with a zero-exclusive-access period.\r\n\r\nThis research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with program #15117.\r\n\r\nThe JWST and HST data presented in this article were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via doi:10.17909/ydwx-st06.\r\n\r\nThis work is based in part on observations made with the Spitzer Space Telescope, which was operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The Spitzer data used in this work can be found in doi:10.26131/IRSA3.\r\n\r\nThis work was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #25-659 “Little Red Dots, Big Open Questions.”\r\n\r\nJWST cartoon in Figure 6, credit: NASA.\r\n\r\nFacilities: VLT:Kueyen - Very Large Telescope (Kueyen) (X-Shooter), VLT:Yepun (HAWK-I), JWST - James Webb Space Telescope (NIRCam, NIRspec), HST - Hubble Space Telescope satellite (ACS), Spitzer - Spitzer Space Telescope satellite (IRAC, MIPS) - .\r\n\r\nSoftware: astropy (Astropy Collaboration et al. 2013, 2018; Astropy Collaboration et al. 2022), NumPy (C. R. Harris et al. 2020), SciPy (P. Virtanen et al. 2020), pysersic (I. Pasha & T. B. Miller 2023), stpsf (M. D. Perrin et al. 2014), lmfit (M. Newville et al. 2014), EsoRex (ESO CPL Development Team 2015), Claude (used for Python coding; https://claude.ai/), SEP (K. Barbary 2016)." date_created: 2026-07-12T22:02:17Z date_published: 2026-07-10T00:00:00Z date_updated: 2026-07-13T08:08:41Z day: '10' ddc: - '520' department: - _id: JoMa - _id: IlCa - _id: GradSch doi: 10.3847/2041-8213/ae7bfd external_id: arxiv: - '2603.28335' file: - access_level: open_access checksum: 7600db260d799ddea45cf3bd01effe41 content_type: application/pdf creator: dernst date_created: 2026-07-13T07:46:22Z date_updated: 2026-07-13T07:46:22Z file_id: '22274' file_name: 2026_AstrophysicalJourLetters_Torralba.pdf file_size: 5419071 relation: main_file success: 1 file_date_updated: 2026-07-13T07:46:22Z has_accepted_license: '1' intvolume: ' 1005' issue: '2' language: - iso: eng month: '07' oa: 1 oa_version: Published Version project: - _id: bd9b2118-d553-11ed-ba76-db24564edfea grant_number: '101076224' name: Young galaxies as tracers and agents of cosmic reionization publication: The Astrophysical Journal Letters publication_identifier: eissn: - 2041-8213 issn: - 2041-8205 publication_status: published publisher: IOP Publishing quality_controlled: '1' researchdata_availability: yes scopus_import: '1' status: public supplementarymaterial: yes title: 'A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 1005 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '22270' abstract: - lang: eng text: "The explosion of a white dwarf (WD) in a close binary can launch a surviving runaway star at\r\nvelocities of ≳ 1000 km s−1\r\n. Such runaways provide a direct probe of thermonuclear supernovae (SNe)\r\nin double-degenerate binaries. Several candidate runaways are known, but their evolutionary states\r\nand the demographics of the broader population are uncertain. To enable robust population inference,\r\nwe carry out a systematic survey for hypervelocity runaways with a simple selection function, selecting\r\ncandidates based on large Gaia-inferred tangential velocities and blue colors. We classify 100% of the\r\nresulting 92 candidates using a combination of spectroscopic follow-up and archival data. The search\r\nyields ten suspected D6\r\nstars and three LP 40-365 stars. Three D6\r\nstars are new discoveries, including\r\ntwo hot (Teff ≳ 50,000 K) objects and one cool (Teff ≈ 7,000 K) object. We forward-model our survey\r\nunder several proposed D6\r\nstar evolutionary models, coupling each to a Galactic model and the survey\r\nselection function. No single model reproduces the observed diversity of D6\r\nstars, which likely reflects\r\na range of remnant masses, ages, and heating mechanisms. Models in which runaway companions\r\nare heated by SN shocks alone are too faint and short-lived to explain most of the observed sample,\r\nwhile fully reheated models are too luminous and long-lived. Models with intermediate heating,\r\nas occurs in some simulations of violent mergers and partially disrupted remnants, best match the\r\nobserved magnitude, distance, and kinematic-age distributions. The inferred D6\r\nstar birth rate is\r\nmodel dependent, but the models that best match the observed population require rates of only a\r\nfew percent of the Galactic SN Ia rate, perhaps implying that most SNe Ia result from WD binaries\r\nin which both components explode. If most SNe Ia do produce surviving runaways, these must be\r\nfainter or shorter-lived than the currently known runaways." acknowledgement: "We thank Lars Bildsten, Evan Bauer, Ruediger Pakmor, Jim Fuller, Logan Proust, Abinaya Rajamuthukumar, and Stephan Geier for useful discussion related to\r\nthis work.\r\nThis work was supported by NSF grants AST-2508988\r\nand AST-2205631, NASA/ESA Hubble Space Telescope\r\nprogram No. 17441, and Scialog grant #SA-LSST-2024-\r\n114c from the Research Corporation for Science Advancement. The Kavli Institute for Theoretical Physics\r\n(KITP) hosted the program, “White Dwarfs as Probes of\r\nthe Evolution of Planets, Stars, the Milky Way, and the\r\nExpanding Universe,” during which this project was initiated. This research was supported in part by the U.S.\r\nNational Science Foundation (NSF) under grants PHY1748958. This research benefited from discussions that\r\nwere funded by the Gordon and Betty Moore Foundation\r\nthrough Grant GBMF5076.\r\nWe thank the staffs of the various observatories at\r\nwhich data were obtained. This work is partially based\r\non observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project\r\nof the Minist´erio da Ciˆencia, Tecnologia e Inova¸c˜oes\r\n(MCTI/LNA) do Brasil, the US National Science Foundation’s NOIRLab, the University of North Carolina\r\nat Chapel Hill (UNC), and Michigan State University\r\n(MSU). Some of the data presented herein were obtained\r\nat the W. M. Keck Observatory, which is operated as a\r\nscientific partnership among the California Institute of\r\nTechnology, the University of California, and NASA; the observatory was made possible by the generous financial\r\nsupport of the W. M. Keck Foundation.\r\nThis research has made use of the Keck Observatory\r\nArchive (KOA), which is operated by the W. M. Keck\r\nObservatory and the NASA Exoplanet Science Institute\r\n(NExScI), under contract with the National Aeronautics\r\nand Space Administration.\r\nThis work has made use of data from the\r\nEuropean Space Agency (ESA) mission Gaia\r\n(https://www.cosmos.esa.int/gaia), processed\r\nby the Gaia Data Processing and Analysis Consortium\r\n(DPAC, https://www.cosmos.esa.int/web/gaia/\r\ndpac/consortium). Funding for the DPAC has been\r\nprovided by national institutions, in particular the\r\ninstitutions participating in the Gaia Multilateral\r\nAgreement." article_processing_charge: No article_type: original arxiv: 1 author: - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Klaus full_name: Werner, Klaus last_name: Werner - first_name: Ken J. full_name: Shen, Ken J. last_name: Shen - first_name: Jay full_name: Strader, Jay last_name: Strader - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Jiwon Jesse full_name: Han, Jiwon Jesse last_name: Han - first_name: Vedant full_name: Chandra, Vedant last_name: Chandra - first_name: Laura full_name: Chomiuk, Laura last_name: Chomiuk - first_name: Zachary P. full_name: Vanderbosch, Zachary P. last_name: Vanderbosch - first_name: Lisa full_name: Blomberg, Lisa last_name: Blomberg - first_name: Natsuko full_name: Yamaguchi, Natsuko last_name: Yamaguchi - first_name: Pranav full_name: Nagarajan, Pranav last_name: Nagarajan - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Joannes C full_name: van Roestel, Joannes C id: 4d122fc8-6083-11f0-87a5-97d68b860333 last_name: van Roestel - first_name: Hila full_name: Glanz, Hila last_name: Glanz - first_name: Tin Long Sunny full_name: Wong, Tin Long Sunny last_name: Wong - first_name: Aakash full_name: Bhat, Aakash last_name: Bhat - first_name: Mark A. full_name: Hollands, Mark A. last_name: Hollands citation: ama: El-Badry K, Werner K, Shen KJ, et al. A systematic survey for hypervelocity runaways from thermonuclear supernovae. The Open Journal of Astrophysics. 2026;9. doi:10.33232/001c.164326 apa: El-Badry, K., Werner, K., Shen, K. J., Strader, J., Rodriguez, A. C., Han, J. J., … Hollands, M. A. (2026). A systematic survey for hypervelocity runaways from thermonuclear supernovae. The Open Journal of Astrophysics. Maynooth Academic Publishing. https://doi.org/10.33232/001c.164326 chicago: El-Badry, Kareem, Klaus Werner, Ken J. Shen, Jay Strader, Antonio C. Rodriguez, Jiwon Jesse Han, Vedant Chandra, et al. “A Systematic Survey for Hypervelocity Runaways from Thermonuclear Supernovae.” The Open Journal of Astrophysics. Maynooth Academic Publishing, 2026. https://doi.org/10.33232/001c.164326. ieee: K. El-Badry et al., “A systematic survey for hypervelocity runaways from thermonuclear supernovae,” The Open Journal of Astrophysics, vol. 9. Maynooth Academic Publishing, 2026. ista: El-Badry K, Werner K, Shen KJ, Strader J, Rodriguez AC, Han JJ, Chandra V, Chomiuk L, Vanderbosch ZP, Blomberg L, Yamaguchi N, Nagarajan P, Caiazzo I, van Roestel JC, Glanz H, Wong TLS, Bhat A, Hollands MA. 2026. A systematic survey for hypervelocity runaways from thermonuclear supernovae. The Open Journal of Astrophysics. 9. mla: El-Badry, Kareem, et al. “A Systematic Survey for Hypervelocity Runaways from Thermonuclear Supernovae.” The Open Journal of Astrophysics, vol. 9, Maynooth Academic Publishing, 2026, doi:10.33232/001c.164326. short: K. El-Badry, K. Werner, K.J. Shen, J. Strader, A.C. Rodriguez, J.J. Han, V. Chandra, L. Chomiuk, Z.P. Vanderbosch, L. Blomberg, N. Yamaguchi, P. Nagarajan, I. Caiazzo, J.C. van Roestel, H. Glanz, T.L.S. Wong, A. Bhat, M.A. Hollands, The Open Journal of Astrophysics 9 (2026). das_tickbox: '1' dataavailabilitystatement: "We thank the staffs of the various observatories at\r\nwhich data were obtained. This work is partially based\r\non observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project\r\nof the Minist´erio da Ciˆencia, Tecnologia e Inova¸c˜oes\r\n(MCTI/LNA) do Brasil, the US National Science Foundation’s NOIRLab, the University of North Carolina\r\nat Chapel Hill (UNC), and Michigan State University\r\n(MSU). Some of the data presented herein were obtained\r\nat the W. M. Keck Observatory, which is operated as a\r\nscientific partnership among the California Institute of\r\nTechnology, the University of California, and NASA; the\r\nobservatory was made possible by the generous financial\r\nsupport of the W. M. Keck Foundation.\r\nThis research has made use of the Keck Observatory\r\nArchive (KOA), which is operated by the W. M. Keck\r\nObservatory and the NASA Exoplanet Science Institute\r\n(NExScI), under contract with the National Aeronautics\r\nand Space Administration.\r\nThis work has made use of data from the\r\nEuropean Space Agency (ESA) mission Gaia\r\n(https://www.cosmos.esa.int/gaia), processed\r\nby the Gaia Data Processing and Analysis Consortium\r\n(DPAC, https://www.cosmos.esa.int/web/gaia/\r\ndpac/consortium). Funding for the DPAC has been\r\nprovided by national institutions, in particular the\r\ninstitutions participating in the Gaia Multilateral\r\nAgreement." date_created: 2026-07-12T22:02:19Z date_published: 2026-06-30T00:00:00Z date_updated: 2026-07-13T09:09:34Z day: '30' ddc: - '520' department: - _id: IlCa doi: 10.33232/001c.164326 external_id: arxiv: - '2606.11293' file: - access_level: open_access checksum: 6320fd19e5ea3399f332be5aab022736 content_type: application/pdf creator: dernst date_created: 2026-07-13T09:05:36Z date_updated: 2026-07-13T09:05:36Z file_id: '22282' file_name: 2026_OpenJourAstrophysics_ElBadry.pdf file_size: 1994596 relation: main_file success: 1 file_date_updated: 2026-07-13T09:05:36Z has_accepted_license: '1' intvolume: ' 9' keyword: - white dwarfs - 'binaries: close' - 'stars: chemically peculiar' language: - iso: eng month: '06' oa: 1 oa_version: Published Version publication: The Open Journal of Astrophysics publication_identifier: eissn: - 2565-6120 publication_status: published publisher: Maynooth Academic Publishing quality_controlled: '1' researchdata_availability: no scopus_import: '1' status: public supplementarymaterial: no title: A systematic survey for hypervelocity runaways from thermonuclear supernovae tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 9 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '22303' abstract: - lang: eng text: "We present the discovery of AT 2024wpp (‘Whippet’), a fast and luminous 18cow-like transient. At a redshift of z = 0 . 0868 , revealed by Keck Cosmic Web Imager spectroscopy of its faint star-forming host, it is the fourth-nearest example of its class to date. Rapid identification of the source in the Zwicky Transient Facility data stream permitted ultraviolet-through- optical observations to be obtained prior to peak, allowing the first determination of the peak bolometric luminosity ( 2 ×1045 erg s−1 ), maximum photospheric radius ( 1015 cm), and total radiated energy ( 1051 erg) of an 18cow-like object. We present results from a comprehensive multiwavelength observing campaign, including a far-ultraviolet spectrum from the Cosmic Origins Spectrograph on the Hubble Space Telescope and deep imaging extending > 100 d post-explosion from the Very Large Telescope, Hubble Space Telescope , Very Large Array, and Atacama Large Millimetre Array. We interpret the observations under a model in which a rapidly accreting central engine blows a fast ( ∼0.2 c ) wind into the surrounding medium and irradiates it with X-rays. The high Doppler velocities and intense ionization within this wind prevent identifiable spectroscopic features from appearing in the ejecta or in the surrounding circumstellar material. Weak H and He signatures do emerge in the spectra after 35 d in the form of double-peaked narrow lines. Each peak is individually narrow (full width δv ∼3000 km s−1 ) but the two components are separated by \x03v ∼6600 km s−1 , indicating stable structures of denser material, possibly representing streams of tidal ejecta or an ablated companion star." acknowledgement: "We thank Eliot Quataert, Luc Dessart, Ben Margalit, Ross Ferguson, Aaron Tohuvavohu, Brad Cenko, and Jamie Kennea for useful discussions. We thank the referee for helpful suggestions that improved the manuscript.\r\n\r\nBased on observations obtained with the Samuel Oschin Telescope 48-in. and the 60-in. Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant no. AST-2034437 and a collaboration including Caltech, IPAC, the Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley, the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University Bochum, Cornell University, Northwestern University and Drexel University. Operations are conducted by COO, IPAC, and UW.\r\n\r\nThe Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council.\r\n\r\nBased on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The NOT data were obtained under program ID 68–501.\r\n\r\nThis work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. We are grateful to Phil Evans, Aaron Tohuvavohu, and Jamie Kennea for advice on the Swift/XRT data reduction.\r\n\r\nSome of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\r\n\r\nSome observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.\r\n\r\nThe National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This paper makes use of the following ALMA data: ADS/JAO.ALMA no. 2023.1.01730.T ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ.\r\n\r\nBased on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 2114.D-5014(E). We thank John Pritchard and Paula Sanchez Saez, and the entire observatory staff, for their excellent support.\r\n\r\nBased on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of ePESSTO+ (the advanced Public ESO Spectroscopic Survey for Transient Objects Survey – PI: Inserra). ePESSTO+ observations were obtained under ESO program ID 112.25JQ.\r\n\r\nThis research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with programs 16714, 17477, and 17889.\r\n\r\nBased on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia e Inovações (MCTI/LNA) do Brasil, the US National Science Foundation’s NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).\r\n\r\nThe Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant no. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation grant no. AST–1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation.\r\n\r\nThis research made use of ccdproc, an astropy package for image reduction (M. Craig et al. 2025).\r\n\r\nGS and AYQH acknowledge support in part from a Sloan Research Fellowship (award no. FG-2024-21320) from the Alfred P. Sloan Foundation. CS and AYQH acknowledge support in part from National Aeronautics and Space Administration (NASA) grant 80NSSC24K0377, from HST grant HST-GO-17477.006-A, and from a Scialog award from the Research Corporation for Science Advancement (‘Early Science with the LSST’).\r\n\r\nPC acknowledges support from the Zhejiang Provincial Top-Level Research Support Program.\r\n\r\nIA and JC are supported by the National Science Foundation award AST 2505775, NASA grant 24-ADAP24-0159, Scialog award SA-LSST-2024-102a, and the Discovery Alliance Catalyst Fellowship Mentors award 2025-62192-CM-19\r\n\r\nAA acknowledges support from the Ministry of Education Yushan Fellow Program (MOE-111-YSFMS-0008-001-P1) and from the National Science and Technology Council, Taiwan (NSTC 114-2112-M-008-021-MY3).\r\n\r\nT-WC acknowledges support from the Ministry of Education Yushan Fellow Program (MOE-111-YSFMS-0008-001-P1) and from the National Science and Technology Council, Taiwan (NSTC 114-2112-M-008-021-MY3).\r\n\r\nERC acknowledges support from the National Aeronautics and Space Administration through the Astrophysics Theory Program, grant 80NSSC24K0897.\r\n\r\nGD acknowledges support from the European Union’s Horizon Europe research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 101199369.\r\n\r\nDF’s contribution to this material is based upon work supported by the National Science Foundation under award no. AST-2401779.\r\n\r\nAGY’s research is supported by ISF, IMOS, and BSF grants, as well as the André Deloro Institute for Space and Optics Research, the Center for Experimental Physics, a WIS-MIT Sagol grant, the Norman E Alexander Family M Foundation ULTRASAT Data Center Fund, and Yeda-Sela; AGY is the incumbent of the The Arlyn Imberman Professorial Chair.\r\n\r\nLG acknowledges financial support from AGAUR, CSIC, MCIN, and AEI 10.13039/501100011033 under projects PID2023-151307NB-I00, PIE 20215AT016, and CEX2020-001058-M.\r\n\r\nMG acknowledges support from an STFC PhD studentship and from the Faculty of Science and Technology at Lancaster University.\r\n\r\nCPG acknowledges financial support from the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2023-151307NB-I00 SNNEXT project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016 and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M, and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant.\r\n\r\nCL is supported by DoE award no.  DE-SC0025599.\r\n\r\nZwicky Transient Facility, W. M. Keck Observatory, and MMT Observatory access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).\r\n\r\nAM gratefully acknowledges support from an STFC PhD studentship and the Faculty of Science and Technology at Lancaster University.\r\n\r\nTEMB is funded by Horizon Europe ERC grant no. 101125877.\r\n\r\nMN is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 948381).\r\n\r\nNR is supported by a Northwestern University Presidential Fellowship Award. We gratefully acknowledge the support of the NSF-Simons AI-Institute for the Sky (SkAI) via grants NSF AST-2421845 and Simons Foundation MPS-AI-00010513.\r\n\r\nAS acknowledges the Warwick Astrophysics PhD prize scholarship made possible thanks to a generous philanthropic donation.\r\n\r\nSJS acknowledges funding from STFC grant ST/Y001605/1, a Royal Society Research Professorship and the Hintze Family Charitable Foundation." article_number: stag678 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Daniel A full_name: Perley, Daniel A last_name: Perley - first_name: Anna Y Q full_name: Ho, Anna Y Q last_name: Ho - first_name: Zoë full_name: McGrath, Zoë last_name: McGrath - first_name: Michael full_name: Camilo, Michael last_name: Camilo - first_name: Cassie full_name: Sevilla, Cassie last_name: Sevilla - first_name: Ping full_name: Chen, Ping last_name: Chen - first_name: Genevieve full_name: Schroeder, Genevieve last_name: Schroeder - first_name: Taya full_name: Govreen-Segal, Taya last_name: Govreen-Segal - first_name: Aleksandra full_name: Bochenek, Aleksandra last_name: Bochenek - first_name: Yu-Jing full_name: Qin, Yu-Jing last_name: Qin - first_name: James H full_name: Gillanders, James H last_name: Gillanders - first_name: Benjamin full_name: Amend, Benjamin last_name: Amend - first_name: Joseph P full_name: Anderson, Joseph P last_name: Anderson - first_name: Igor full_name: Andreoni, Igor last_name: Andreoni - first_name: Amar full_name: Aryan, Amar last_name: Aryan - first_name: Eric C full_name: Bellm, Eric C last_name: Bellm - first_name: Joshua S full_name: Bloom, Joshua S last_name: Bloom - first_name: Thomas full_name: de Boer, Thomas last_name: de Boer - first_name: Jonathan full_name: Carney, Jonathan last_name: Carney - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Ken C full_name: Chambers, Ken C last_name: Chambers - first_name: Panos full_name: Charalampopoulos, Panos last_name: Charalampopoulos - first_name: Ting-Wan full_name: Chen, Ting-Wan last_name: Chen - first_name: Tracy X full_name: Chen, Tracy X last_name: Chen - first_name: Eric R full_name: Coughlin, Eric R last_name: Coughlin - first_name: Michael full_name: Coughlin, Michael last_name: Coughlin - first_name: Michel full_name: Dennefeld, Michel last_name: Dennefeld - first_name: Georgios full_name: Dimitriadis, Georgios last_name: Dimitriadis - first_name: Christoffer full_name: Fremling, Christoffer last_name: Fremling - first_name: Danielle full_name: Frostig, Danielle last_name: Frostig - first_name: Avishay full_name: Gal-Yam, Avishay last_name: Gal-Yam - first_name: Lluís full_name: Galbany, Lluís last_name: Galbany - first_name: Anjashay full_name: Gangopadhyay, Anjashay last_name: Gangopadhyay - first_name: Melzie full_name: Ghendrih, Melzie last_name: Ghendrih - first_name: Matthew J full_name: Graham, Matthew J last_name: Graham - first_name: Mariusz full_name: Gromadzki, Mariusz last_name: Gromadzki - first_name: Steven L full_name: Groom, Steven L last_name: Groom - first_name: Claudia P full_name: Gutiérrez, Claudia P last_name: Gutiérrez - first_name: K -Ryan full_name: Hinds, K -Ryan last_name: Hinds - first_name: Mark E full_name: Huber, Mark E last_name: Huber - first_name: Cosimo full_name: Inserra, Cosimo last_name: Inserra - first_name: Benjamin C full_name: Kaiser, Benjamin C last_name: Kaiser - first_name: Mansi M full_name: Kasliwal, Mansi M last_name: Kasliwal - first_name: Niilo E full_name: Koivisto, Niilo E last_name: Koivisto - first_name: Chien-Cheng full_name: Lin, Chien-Cheng last_name: Lin - first_name: Chang full_name: Liu, Chang last_name: Liu - first_name: Thomas B full_name: Lowe, Thomas B last_name: Lowe - first_name: Eugene full_name: Magnier, Eugene last_name: Magnier - first_name: Ashish A full_name: Mahabal, Ashish A last_name: Mahabal - first_name: Andrew full_name: Milligan, Andrew last_name: Milligan - first_name: Paloma full_name: Minguez, Paloma last_name: Minguez - first_name: Geoffrey full_name: Mo, Geoffrey last_name: Mo - first_name: Tomás E full_name: Müller-Bravo, Tomás E last_name: Müller-Bravo - first_name: Matt full_name: Nicholl, Matt last_name: Nicholl - first_name: Priscila J full_name: Pessi, Priscila J last_name: Pessi - first_name: Giuliano full_name: Pignata, Giuliano last_name: Pignata - first_name: Josiah full_name: Purdum, Josiah last_name: Purdum - first_name: Nabeel full_name: Rehemtulla, Nabeel last_name: Rehemtulla - first_name: R Michael full_name: Rich, R Michael last_name: Rich - first_name: Anwesha full_name: Sahu, Anwesha last_name: Sahu - first_name: Avinash full_name: Singh, Avinash last_name: Singh - first_name: Stephen J full_name: Smartt, Stephen J last_name: Smartt - first_name: Ian A full_name: Smith, Ian A last_name: Smith - first_name: Jesper full_name: Sollerman, Jesper last_name: Sollerman - first_name: Gokul full_name: Srinivasaragavan, Gokul last_name: Srinivasaragavan - first_name: Shubham full_name: Srivastav, Shubham last_name: Srivastav - first_name: Robert D full_name: Stein, Robert D last_name: Stein - first_name: Steve full_name: Schulze, Steve last_name: Schulze - first_name: Jack W full_name: Tweddle, Jack W last_name: Tweddle - first_name: Richard full_name: Wainscoat, Richard last_name: Wainscoat - first_name: Jacob L full_name: Wise, Jacob L last_name: Wise - first_name: Lin full_name: Yan, Lin last_name: Yan - first_name: David R full_name: Young, David R last_name: Young citation: ama: 'Perley DA, Ho AYQ, McGrath Z, et al. AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. 2026;549(1). doi:10.1093/mnras/stag678' apa: 'Perley, D. A., Ho, A. Y. Q., McGrath, Z., Camilo, M., Sevilla, C., Chen, P., … Young, D. R. (2026). AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/stag678' chicago: 'Perley, Daniel A, Anna Y Q Ho, Zoë McGrath, Michael Camilo, Cassie Sevilla, Ping Chen, Genevieve Schroeder, et al. “AT 2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2026. https://doi.org/10.1093/mnras/stag678.' ieee: 'D. A. Perley et al., “AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole,” Monthly Notices of the Royal Astronomical Society, vol. 549, no. 1. Oxford University Press, 2026.' ista: 'Perley DA, Ho AYQ, McGrath Z, Camilo M, Sevilla C, Chen P, Schroeder G, Govreen-Segal T, Bochenek A, Qin Y-J, Gillanders JH, Amend B, Anderson JP, Andreoni I, Aryan A, Bellm EC, Bloom JS, de Boer T, Carney J, Caiazzo I, Chambers KC, Charalampopoulos P, Chen T-W, Chen TX, Coughlin ER, Coughlin M, Dennefeld M, Dimitriadis G, Fremling C, Frostig D, Gal-Yam A, Galbany L, Gangopadhyay A, Ghendrih M, Graham MJ, Gromadzki M, Groom SL, Gutiérrez CP, Hinds K-R, Huber ME, Inserra C, Kaiser BC, Kasliwal MM, Koivisto NE, Lin C-C, Liu C, Lowe TB, Magnier E, Mahabal AA, Milligan A, Minguez P, Mo G, Müller-Bravo TE, Nicholl M, Pessi PJ, Pignata G, Purdum J, Rehemtulla N, Rich RM, Sahu A, Singh A, Smartt SJ, Smith IA, Sollerman J, Srinivasaragavan G, Srivastav S, Stein RD, Schulze S, Tweddle JW, Wainscoat R, Wise JL, Yan L, Young DR. 2026. AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. 549(1), stag678.' mla: 'Perley, Daniel A., et al. “AT 2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole.” Monthly Notices of the Royal Astronomical Society, vol. 549, no. 1, stag678, Oxford University Press, 2026, doi:10.1093/mnras/stag678.' short: D.A. Perley, A.Y.Q. Ho, Z. McGrath, M. Camilo, C. Sevilla, P. Chen, G. Schroeder, T. Govreen-Segal, A. Bochenek, Y.-J. Qin, J.H. Gillanders, B. Amend, J.P. Anderson, I. Andreoni, A. Aryan, E.C. Bellm, J.S. Bloom, T. de Boer, J. Carney, I. Caiazzo, K.C. Chambers, P. Charalampopoulos, T.-W. Chen, T.X. Chen, E.R. Coughlin, M. Coughlin, M. Dennefeld, G. Dimitriadis, C. Fremling, D. Frostig, A. Gal-Yam, L. Galbany, A. Gangopadhyay, M. Ghendrih, M.J. Graham, M. Gromadzki, S.L. Groom, C.P. Gutiérrez, K.-R. Hinds, M.E. Huber, C. Inserra, B.C. Kaiser, M.M. Kasliwal, N.E. Koivisto, C.-C. Lin, C. Liu, T.B. Lowe, E. Magnier, A.A. Mahabal, A. Milligan, P. Minguez, G. Mo, T.E. Müller-Bravo, M. Nicholl, P.J. Pessi, G. Pignata, J. Purdum, N. Rehemtulla, R.M. Rich, A. Sahu, A. Singh, S.J. Smartt, I.A. Smith, J. Sollerman, G. Srinivasaragavan, S. Srivastav, R.D. Stein, S. Schulze, J.W. Tweddle, R. Wainscoat, J.L. Wise, L. Yan, D.R. Young, Monthly Notices of the Royal Astronomical Society 549 (2026). das_tickbox: '1' dataavailabilitystatement: All photometry is provided in the supplementary data files. Spectroscopy will be made available on WISEREP, and is available on request to the lead author. date_created: 2026-07-13T10:50:10Z date_published: 2026-06-01T00:00:00Z date_updated: 2026-07-13T14:36:24Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1093/mnras/stag678 external_id: arxiv: - '2601.03337' file: - access_level: open_access checksum: a5827b9f68f1731b8c8df18142c0ef38 content_type: application/pdf creator: dernst date_created: 2026-07-13T14:35:34Z date_updated: 2026-07-13T14:35:34Z file_id: '22314' file_name: 2026_MNRAS_Perley.pdf file_size: 6208809 relation: main_file success: 1 file_date_updated: 2026-07-13T14:35:34Z has_accepted_license: '1' intvolume: ' 549' issue: '1' keyword: - 'stars: black holes' - 'supernovae: individual: AT2024wpp' - 'radio continuum: transients' language: - iso: eng month: '06' oa: 1 oa_version: Published Version publication: Monthly Notices of the Royal Astronomical Society publication_identifier: eissn: - 1365-2966 issn: - 0035-8711 publication_status: published publisher: Oxford University Press quality_controlled: '1' researchdata_availability: upon request scopus_import: '1' status: public supplementarymaterial: yes title: 'AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 549 year: '2026' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '22675' abstract: - lang: eng text: "Tidal disruption events (TDEs) have traditionally been discovered in optical sky surveys through targeted searches of nuclear transients. However, it is expected that some TDEs will occur outside the galaxy nucleus, arising from wandering black holes (BHs) originating in galaxy mergers. Here, we present observations of TDE 2025abcr, the first optical TDE discovered in the outskirts of a host galaxy. The TDE was identified by a custom “off-nuclear” implementation of the machine learning classifier tdescore, which classifies new ZTF transients based on their lightcurves. Follow-up observations confirm that TDE 2025abcr is a TDE-H+He, occurring 9\r\n5 (9.3 kpc projected distance) from the nucleus of a massive galaxy (M⋆ = 1011.18±0.03M⊙) with a central BH mass of 108.82±0.65M⊙. TDE 2025abcr itself was likely disrupted by a much lighter BH (106.09±0.53M⊙, as estimated with peak luminosity scaling relations). The BH was either dynamically ejected from the nucleus or lies at the center of a very faint tidally stripped dwarf galaxy undergoing a minor merger. Late-time observations of TDE 2025abcr could confirm the origin of this apparent “wandering” BH. The rate of highly offset (≳3 kpc) TDEs can be constrained to <10% of the nuclear TDE rate, but our discovery implies that many dozens of similar sources will be detected by the Vera C. Rubin Observatory each year with resolvable offsets." acknowledgement: "We thank Muryel Guolo, Dan Perley, and Carl Rodriguez for the fruitful discussions about off-nuclear TDEs.\r\n\r\nBased on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the ZTF project. ZTF is supported by the National Science Foundation under award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan, and the German Center for Astrophysics (DZA), Germany. Operations are conducted by Caltech’s Optical Observatory (COO), Caltech/IPAC, and the University of Washington at Seattle, USA.\r\n\r\nSED Machine is based upon work supported by the National Science Foundation under grant No. 1106171.\r\n\r\nThe Gordon and Betty Moore Foundation, through both the Data-Driven Investigator Program and a dedicated grant, provided critical funding for SkyPortal.\r\n\r\nThese results were obtained with the use of LDT, owned and operated by the Lowell Observatory\r\n\r\nSome of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 nonprofit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.\r\n\r\nA major upgrade of the Kast spectrograph on the Shane 3 m telescope at Lick Observatory, led by Brad Holden, was made possible through gifts from the Heising-Simons Foundation, William and Marina Kast, and the University of California Observatories. Research at Lick Observatory is partially supported by a generous gift from Google.\r\n\r\nThis work is based (in part) on observations made with NOT, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias under NOT programmes 72-504. The NOT data presented here were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT.\r\n\r\nThis work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester.\r\n\r\nThis paper contains data obtained at the Wendelstein Observatory of the Ludwig-Maximilians University Munich. We thank Christoph Ries for carrying out the observations. Funded in part by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy—EXC-2094/2—390783311.\r\n\r\nThe national facility capability for SkyMapper has been funded through ARC LIEF grant LE130100104 from the Australian Research Council, awarded to the University of Sydney, the Australian National University, Swinburne University of Technology, the University of Queensland, the University of Western Australia, the University of Melbourne, Curtin University of Technology, Monash University, and the Australian Astronomical Observatory. SkyMapper is owned and operated by The Australian National University’s Research School of Astronomy and Astrophysics. The survey data were processed and provided by the SkyMapper Team at ANU. The SkyMapper node of the All-Sky Virtual Observatory (ASVO) is hosted at the National Computational Infrastructure (NCI). Development and support of the SkyMapper node of the ASVO has been funded in part by Astronomy Australia Limited (AAL) and the Australian Government through the Commonwealth’s Education Investment Fund (EIF) and National Collaborative Research Infrastructure Strategy (NCRIS), particularly the National eResearch Collaboration Tools and Resources (NeCTAR) and the Australian National Data Service Projects (ANDS).\r\n\r\nThe National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the NRAO for carrying out the Karl G. Jansky VLA observation.\r\n\r\nNote Added - Shortly before this work was accepted, we became aware of a later preprint by K. Patra et al. (2026). The work reaches many similar conclusions to our own, and presents additional JWST data of TDE 2025abcr. We also thank the authors for highlighting a typo on an earlier version of this manuscript, with the projected offset incorrectly given as 10.3 kpc rather than 9.3 kpc.\r\n\r\nFacilities: PO:1.2m - Palomar Observatory's 1.2 meter Samuel Oschin Telescope (ZTF), Hale - Palomar Observatory's 5.1m Hale Telescope (protoCerberus), Keck:I - KECK I Telescope (LRIS), LDT - (DeVeney, LMI), NOT - Nordic Optical Telescope (ALFOSC), PO:1.5m - Palomar Observatory's 1.5 meter Telescope (SEDM), SOAR - The Southern Astrophysical Research Telescope (Goodman), Swift - Swift Gamma-Ray Burst Mission (XRT, UVOT) - , VLA - Very Large Array, WO:2m - (3KK).\r\n\r\nSoftware: astroquery (B. D. Johnson et al. 2021), emcee (D. Foreman-Mackey et al. 2013), HEASoft, galsynthspec (R. D. Stein 2025), mirar (R. D. Stein et al. 2025), prospector (B. D. Johnson et al. 2021), SCAMP (E. Bertin 2006), scarlet (P. Melchior et al. 2018), Source Extractor (E. Bertin & S. Arnouts 1996), swifttools, tdescore (R. Stein et al. 2024), uvotredux (R. D. Stein & J. Carney 2025)." article_number: L57 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Robert full_name: Stein, Robert last_name: Stein - first_name: Jonathan full_name: Carney, Jonathan last_name: Carney - first_name: Charlotte full_name: Ward, Charlotte last_name: Ward - first_name: Raffaella full_name: Margutti, Raffaella last_name: Margutti - first_name: Xander J. full_name: Hall, Xander J. last_name: Hall - first_name: Itai full_name: Sfaradi, Itai last_name: Sfaradi - first_name: Igor full_name: Andreoni, Igor last_name: Andreoni - first_name: Panos full_name: Charalampopoulos, Panos last_name: Charalampopoulos - first_name: Ryan full_name: Chornock, Ryan last_name: Chornock - first_name: Suvi full_name: Gezari, Suvi last_name: Gezari - first_name: Geoffrey full_name: Mo, Geoffrey last_name: Mo - first_name: Yuhan full_name: Yao, Yuhan last_name: Yao - first_name: Akash full_name: Anumarlapudi, Akash last_name: Anumarlapudi - first_name: Eric C. full_name: Bellm, Eric C. last_name: Bellm - first_name: Joshua S. full_name: Bloom, Joshua S. last_name: Bloom - first_name: Malte full_name: Busmann, Malte last_name: Busmann - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: S. Bradley full_name: Cenko, S. Bradley last_name: Cenko - first_name: Matthew J. full_name: Graham, Matthew J. last_name: Graham - first_name: Steven L. full_name: Groom, Steven L. last_name: Groom - first_name: Daniel full_name: Gruen, Daniel last_name: Gruen - first_name: Erica full_name: Hammerstein, Erica last_name: Hammerstein - first_name: Benjamin C. full_name: Kaiser, Benjamin C. last_name: Kaiser - first_name: Mansi M. full_name: Kasliwal, Mansi M. last_name: Kasliwal - first_name: Brendan full_name: O’Connor, Brendan last_name: O’Connor - first_name: Antonella full_name: Palmese, Antonella last_name: Palmese - first_name: Josiah full_name: Purdum, Josiah last_name: Purdum - first_name: Jillian C. full_name: Rastinejad, Jillian C. last_name: Rastinejad - first_name: Reed full_name: Riddle, Reed last_name: Riddle - first_name: Ben full_name: Rusholme, Ben last_name: Rusholme - first_name: Jesper full_name: Sollerman, Jesper last_name: Sollerman - first_name: Jean J. full_name: Somalwar, Jean J. last_name: Somalwar - first_name: Sylvain full_name: Veilleux, Sylvain last_name: Veilleux citation: ama: 'Stein R, Carney J, Ward C, et al. TDE 2025abcr: A tidal disruption event in the outskirts of a massive galaxy. The Astrophysical Journal Letters. 2026;1006(2). doi:10.3847/2041-8213/ae77f3' apa: 'Stein, R., Carney, J., Ward, C., Margutti, R., Hall, X. J., Sfaradi, I., … Veilleux, S. (2026). TDE 2025abcr: A tidal disruption event in the outskirts of a massive galaxy. The Astrophysical Journal Letters. IOP Publishing. https://doi.org/10.3847/2041-8213/ae77f3' chicago: 'Stein, Robert, Jonathan Carney, Charlotte Ward, Raffaella Margutti, Xander J. Hall, Itai Sfaradi, Igor Andreoni, et al. “TDE 2025abcr: A Tidal Disruption Event in the Outskirts of a Massive Galaxy.” The Astrophysical Journal Letters. IOP Publishing, 2026. https://doi.org/10.3847/2041-8213/ae77f3.' ieee: 'R. Stein et al., “TDE 2025abcr: A tidal disruption event in the outskirts of a massive galaxy,” The Astrophysical Journal Letters, vol. 1006, no. 2. IOP Publishing, 2026.' ista: 'Stein R, Carney J, Ward C, Margutti R, Hall XJ, Sfaradi I, Andreoni I, Charalampopoulos P, Chornock R, Gezari S, Mo G, Yao Y, Anumarlapudi A, Bellm EC, Bloom JS, Busmann M, Caiazzo I, Cenko SB, Graham MJ, Groom SL, Gruen D, Hammerstein E, Kaiser BC, Kasliwal MM, O’Connor B, Palmese A, Purdum J, Rastinejad JC, Riddle R, Rusholme B, Sollerman J, Somalwar JJ, Veilleux S. 2026. TDE 2025abcr: A tidal disruption event in the outskirts of a massive galaxy. The Astrophysical Journal Letters. 1006(2), L57.' mla: 'Stein, Robert, et al. “TDE 2025abcr: A Tidal Disruption Event in the Outskirts of a Massive Galaxy.” The Astrophysical Journal Letters, vol. 1006, no. 2, L57, IOP Publishing, 2026, doi:10.3847/2041-8213/ae77f3.' short: R. Stein, J. Carney, C. Ward, R. Margutti, X.J. Hall, I. Sfaradi, I. Andreoni, P. Charalampopoulos, R. Chornock, S. Gezari, G. Mo, Y. Yao, A. Anumarlapudi, E.C. Bellm, J.S. Bloom, M. Busmann, I. Caiazzo, S.B. Cenko, M.J. Graham, S.L. Groom, D. Gruen, E. Hammerstein, B.C. Kaiser, M.M. Kasliwal, B. O’Connor, A. Palmese, J. Purdum, J.C. Rastinejad, R. Riddle, B. Rusholme, J. Sollerman, J.J. Somalwar, S. Veilleux, The Astrophysical Journal Letters 1006 (2026). das_tickbox: '0' date_created: 2026-08-11T06:19:19Z date_published: 2026-07-27T00:00:00Z date_updated: 2026-08-11T07:45:27Z day: '27' ddc: - '520' department: - _id: IlCa doi: 10.3847/2041-8213/ae77f3 external_id: arxiv: - '2602.10180' file: - access_level: open_access checksum: 42b983f18497bb644f422709de7dc68c content_type: application/pdf creator: dernst date_created: 2026-08-11T07:45:16Z date_updated: 2026-08-11T07:45:16Z file_id: '22682' file_name: 2026_AstrophysicalJourLetters_Stein.pdf file_size: 10322417 relation: main_file success: 1 file_date_updated: 2026-08-11T07:45:16Z has_accepted_license: '1' intvolume: ' 1006' issue: '2' language: - iso: eng month: '07' oa: 1 oa_version: Published Version publication: The Astrophysical Journal Letters publication_identifier: eissn: - 2041-8213 issn: - 2041-8205 publication_status: published publisher: IOP Publishing quality_controlled: '1' researchdata_availability: no scopus_import: '1' status: public supplementarymaterial: yes title: 'TDE 2025abcr: A tidal disruption event in the outskirts of a massive galaxy' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 1006 year: '2026' ... --- OA_place: publisher OA_type: hybrid PlanS_conform: '1' _id: '21241' abstract: - lang: eng text: White dwarfs (WDs) showing transits from orbiting planetary debris provide significant insights into the structure and dynamics of debris disks, which are eventually accreted to produce metal pollution. This is a rare class of objects with only eight published systems. In this work, we perform a systematic search for such systems within 500 pc in the Gaia-eDR3 catalog of WDs using the light curves from the Zwicky Transient Facility (ZTF) and present six new candidates. Our selection process targets the top 1% most photometrically variable sources identified using a combined variability metric from ZTF and Gaia eDR3 photometry, boosted by a metric space we define using von Neumann statistics and Pearson-Skew as a novel discovery tool to identify these systems. This is followed by optical spectroscopic observations of visually selected variables to confirm metal pollution. Four of the six systems show long-timescale photometric variability spanning several months to years, resulting either from long-term evolution of transit activity or dust and debris clouds at wide orbits. Among them, WD J1013–0427 shows an indication of reddening during the long-duration dip. Interpreting this as dust extinction makes it the first system to indicate an abundance of dust grains with radius ≲0.3 μm in the occulting material. The same object also shows metal emission lines that map an optically thick eccentric gas disk orbiting within the star’s Roche limit. For each candidate, we infer the abundances of the photospheric metals and estimate accretion rates. We show that transiting debris systems tend to have higher inferred accretion rates compared to the general population of metal-polluted WDs. Growing the number of these systems will further illuminate such comparative properties in the near future. Separately, we also serendipitously discovered an AM Canis Venaticorum showing a very long-duration outburst—only the fourth such system to be known. acknowledgement: "This work is based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. Z.T.F. is supported by the National Science Foundation under grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley, the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University Bochum, Cornell University, Northwestern University, and Drexel University. Operations are conducted by COO, IPAC, and UW.\r\n\r\nThis work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular, the institutions participating in the Gaia Multilateral Agreement. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.\r\n\r\nThis research has made use of the VizieR catalog access tool, CDS, Strasbourg, France https://vizier.cds.unistra.fr/. The original description of the VizieR service was published in Ochsenbein et al. (2000).\r\n\r\nWe are grateful to the staffs of Palomar and Keck Observatory for assistance with the observations and data management.\r\n\r\nThe authors thank the anonymous referee for very extensive and useful comments which improved the presentation of the paper significantly. S.B. acknowledges the support from the Kishore Vaigyanik Protsahan Yojana (KVPY) scheme of the Department of Science and Technology, Government of India (a former fellowship program for undergraduate studies in basic science) during his undergraduate studies at IISc. S.B. thanks the Summer Undergraduate Research Fellowship (SURF) at Caltech and Shrinivas R. Kulkarni for hosting him as a summer research student in 2022. S.B. acknowledges the financial support from the Wallace L. W. Sargent Graduate Fellowship during the first year of his graduate studies at Caltech. P.E.T. received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program number 101002408. S.X. is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. J.A.G. is supported by the National Science Foundation Graduate Research Fellowship Program under grant No. 2234657. This material is based upon work supported by the National Aeronautics and Space Administration under grant No. 80NSSC23K1068 issued through the Science Mission Directorate.\r\n\r\nWe have used Python packages Numpy (Harris et al. 2020), SciPy (Virtanen et al. 2020), Matplotlib (Hunter 2007), Pandas (The pandas development team 2020), Astropy (Astropy Collaboration et al. 2013, 2018), and Astroquery (Ginsburg et al. 2019) at various stages of this research." article_number: '074202' article_processing_charge: Yes (in subscription journal) article_type: original arxiv: 1 author: - first_name: 'Soumyadeep ' full_name: 'Bhattacharjee, Soumyadeep ' last_name: Bhattacharjee - first_name: Zachary P. full_name: Vanderbosch, Zachary P. last_name: Vanderbosch - first_name: Mark A. full_name: Hollands, Mark A. last_name: Hollands - first_name: Pier-Emmanuel full_name: Tremblay, Pier-Emmanuel last_name: Tremblay - first_name: Siyi full_name: Xu, Siyi last_name: Xu - first_name: Joseph A. full_name: Guidry, Joseph A. last_name: Guidry - first_name: J.J. full_name: Hermes, J.J. last_name: Hermes - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Jan full_name: van Roestel, Jan last_name: van Roestel - first_name: 'Kareem ' full_name: 'El-Badry, Kareem ' last_name: El-Badry - first_name: Andrew J. full_name: Drake, Andrew J. last_name: Drake - first_name: Benjamin R. full_name: Roulston, Benjamin R. last_name: Roulston - first_name: Reed full_name: Riddle, Reed last_name: Riddle - first_name: Ben full_name: Rusholme, Ben last_name: Rusholme - first_name: Steven L. full_name: Groom, Steven L. last_name: Groom - first_name: Roger full_name: Smith, Roger last_name: Smith - first_name: Odette full_name: Toloza, Odette last_name: Toloza citation: ama: 'Bhattacharjee S, Vanderbosch ZP, Hollands MA, et al. A ZTF search for circumstellar debris transits in White Dwarfs: Six new candidates, one with gas disk emission, identified in a novel metric space. Publications of the Astronomical Society of the Pacific. 2025;137(7). doi:10.1088/1538-3873/ade0ea' apa: 'Bhattacharjee, S., Vanderbosch, Z. P., Hollands, M. A., Tremblay, P.-E., Xu, S., Guidry, J. A., … Toloza, O. (2025). A ZTF search for circumstellar debris transits in White Dwarfs: Six new candidates, one with gas disk emission, identified in a novel metric space. Publications of the Astronomical Society of the Pacific. IOP Publishing. https://doi.org/10.1088/1538-3873/ade0ea' chicago: 'Bhattacharjee, Soumyadeep , Zachary P. Vanderbosch, Mark A. Hollands, Pier-Emmanuel Tremblay, Siyi Xu, Joseph A. Guidry, J.J. Hermes, et al. “A ZTF Search for Circumstellar Debris Transits in White Dwarfs: Six New Candidates, One with Gas Disk Emission, Identified in a Novel Metric Space.” Publications of the Astronomical Society of the Pacific. IOP Publishing, 2025. https://doi.org/10.1088/1538-3873/ade0ea.' ieee: 'S. Bhattacharjee et al., “A ZTF search for circumstellar debris transits in White Dwarfs: Six new candidates, one with gas disk emission, identified in a novel metric space,” Publications of the Astronomical Society of the Pacific, vol. 137, no. 7. IOP Publishing, 2025.' ista: 'Bhattacharjee S, Vanderbosch ZP, Hollands MA, Tremblay P-E, Xu S, Guidry JA, Hermes JJ, Caiazzo I, Rodriguez AC, van Roestel J, El-Badry K, Drake AJ, Roulston BR, Riddle R, Rusholme B, Groom SL, Smith R, Toloza O. 2025. A ZTF search for circumstellar debris transits in White Dwarfs: Six new candidates, one with gas disk emission, identified in a novel metric space. Publications of the Astronomical Society of the Pacific. 137(7), 074202.' mla: 'Bhattacharjee, Soumyadeep, et al. “A ZTF Search for Circumstellar Debris Transits in White Dwarfs: Six New Candidates, One with Gas Disk Emission, Identified in a Novel Metric Space.” Publications of the Astronomical Society of the Pacific, vol. 137, no. 7, 074202, IOP Publishing, 2025, doi:10.1088/1538-3873/ade0ea.' short: S. Bhattacharjee, Z.P. Vanderbosch, M.A. Hollands, P.-E. Tremblay, S. Xu, J.A. Guidry, J.J. Hermes, I. Caiazzo, A.C. Rodriguez, J. van Roestel, K. El-Badry, A.J. Drake, B.R. Roulston, R. Riddle, B. Rusholme, S.L. Groom, R. Smith, O. Toloza, Publications of the Astronomical Society of the Pacific 137 (2025). date_created: 2026-02-16T15:10:51Z date_published: 2025-07-09T00:00:00Z date_updated: 2026-02-17T11:35:53Z day: '09' ddc: - '520' department: - _id: IlCa doi: 10.1088/1538-3873/ade0ea external_id: arxiv: - '2502.05502' file: - access_level: open_access checksum: 237eddc36e3823b3092fab6aa5bc8655 content_type: application/pdf creator: dernst date_created: 2026-02-17T11:30:29Z date_updated: 2026-02-17T11:30:29Z file_id: '21289' file_name: 2025_PASP_Bhattacharjee.pdf file_size: 8900420 relation: main_file success: 1 file_date_updated: 2026-02-17T11:30:29Z has_accepted_license: '1' intvolume: ' 137' issue: '7' language: - iso: eng license: https://creativecommons.org/licenses/by/3.0/ month: '07' oa: 1 oa_version: Published Version publication: Publications of the Astronomical Society of the Pacific publication_identifier: issn: - 1538-3873 publication_status: published publisher: IOP Publishing quality_controlled: '1' status: public title: 'A ZTF search for circumstellar debris transits in White Dwarfs: Six new candidates, one with gas disk emission, identified in a novel metric space' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/3.0/legalcode name: Creative Commons Attribution 3.0 Unported (CC BY 3.0) short: CC BY (3.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 137 year: '2025' ... --- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '21317' abstract: - lang: eng text: Accreting white dwarfs (WDs) in close binary systems, commonly known as cataclysmic variables (CVs), with orbital periods below the canonical period minimum (≈80 minutes) are rare. Such short periods can only be reached if the donor star in the CV is either significantly evolved before initiating mass transfer to the WD or is metal-poor. We present optical photometry and spectroscopy of Gaia19bxc, a high-amplitude variable identified as a polar CV with an exceptionally short orbital period of 64.42 minutes—well below the canonical CV period minimum. High-speed photometry confirms persistent double-peaked variability consistent with cyclotron beaming, thus indicating the presence of a magnetic WD. Phase-resolved Keck/Low-Resolution Imaging Spectrometer (LRIS) spectroscopy reveals strong hydrogen and helium emission lines but no donor features, indicating the accretor is a magnetic WD and the donor is hydrogen-rich, but cold and faint. The absence of a detectable donor and the low inferred temperature (≲3500 K) disfavor an evolved donor scenario. Instead, the short period and the system’s halo-like kinematics suggest Gaia19bxc may be the first known metal-poor polar. Because metal-poor donors are more compact than solar-metallicity donors of the same mass, they can reach shorter minimum periods. Gaia19bxc is one of only a handful of known metal-poor CVs below the canonical period minimum and has the shortest period of any such magnetic system discovered to date. acknowledgement: "Based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 nonprofit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have had the opportunity to conduct observations from this mountain. We are grateful to the staff of the Palomar and Keck Observatories for their work in helping us carry out our observations.\r\n\r\nI.G. acknowledges support from Kazan Federal University. A.C.R. acknowledges support from the National Science Foundation via an NSF Graduate Research Fellowship. We thank the anonymous referee for useful comments and suggestions, which contributed to the improvement of this manuscript." article_number: L57 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Ilkham full_name: Galiullin, Ilkham last_name: Galiullin - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Paula full_name: Szkody, Paula last_name: Szkody - first_name: Pranav full_name: Nagarajan, Pranav last_name: Nagarajan - first_name: Samuel full_name: Whitebook, Samuel last_name: Whitebook citation: ama: Galiullin I, Rodriguez AC, El-Badry K, et al. Optical spectroscopy of the most compact accreting binary harboring a magnetic White Dwarf and a hydrogen-rich donor. The Astrophysical Journal Letters. 2025;990(2). doi:10.3847/2041-8213/adff82 apa: Galiullin, I., Rodriguez, A. C., El-Badry, K., Caiazzo, I., Szkody, P., Nagarajan, P., & Whitebook, S. (2025). Optical spectroscopy of the most compact accreting binary harboring a magnetic White Dwarf and a hydrogen-rich donor. The Astrophysical Journal Letters. IOP Publishing. https://doi.org/10.3847/2041-8213/adff82 chicago: Galiullin, Ilkham, Antonio C. Rodriguez, Kareem El-Badry, Ilaria Caiazzo, Paula Szkody, Pranav Nagarajan, and Samuel Whitebook. “Optical Spectroscopy of the Most Compact Accreting Binary Harboring a Magnetic White Dwarf and a Hydrogen-Rich Donor.” The Astrophysical Journal Letters. IOP Publishing, 2025. https://doi.org/10.3847/2041-8213/adff82. ieee: I. Galiullin et al., “Optical spectroscopy of the most compact accreting binary harboring a magnetic White Dwarf and a hydrogen-rich donor,” The Astrophysical Journal Letters, vol. 990, no. 2. IOP Publishing, 2025. ista: Galiullin I, Rodriguez AC, El-Badry K, Caiazzo I, Szkody P, Nagarajan P, Whitebook S. 2025. Optical spectroscopy of the most compact accreting binary harboring a magnetic White Dwarf and a hydrogen-rich donor. The Astrophysical Journal Letters. 990(2), L57. mla: Galiullin, Ilkham, et al. “Optical Spectroscopy of the Most Compact Accreting Binary Harboring a Magnetic White Dwarf and a Hydrogen-Rich Donor.” The Astrophysical Journal Letters, vol. 990, no. 2, L57, IOP Publishing, 2025, doi:10.3847/2041-8213/adff82. short: I. Galiullin, A.C. Rodriguez, K. El-Badry, I. Caiazzo, P. Szkody, P. Nagarajan, S. Whitebook, The Astrophysical Journal Letters 990 (2025). date_created: 2026-02-18T10:17:04Z date_published: 2025-09-08T00:00:00Z date_updated: 2026-02-19T07:27:01Z day: '08' ddc: - '520' department: - _id: IlCa doi: 10.3847/2041-8213/adff82 external_id: arxiv: - '2508.20170' file: - access_level: open_access checksum: f76556d129aa0e9facc85602b0b5b54d content_type: application/pdf creator: dernst date_created: 2026-02-19T07:24:10Z date_updated: 2026-02-19T07:24:10Z file_id: '21329' file_name: 2025_AstrophysicalJournal_Galiullin.pdf file_size: 3772189 relation: main_file success: 1 file_date_updated: 2026-02-19T07:24:10Z has_accepted_license: '1' intvolume: ' 990' issue: '2' language: - iso: eng month: '09' oa: 1 oa_version: Published Version publication: The Astrophysical Journal Letters publication_identifier: eissn: - 2041-8213 issn: - 2041-8205 publication_status: published publisher: IOP Publishing quality_controlled: '1' scopus_import: '1' status: public title: Optical spectroscopy of the most compact accreting binary harboring a magnetic White Dwarf and a hydrogen-rich donor tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 990 year: '2025' ... --- OA_place: publisher OA_type: hybrid _id: '18851' abstract: - lang: eng text: 'We present volume-limited samples of cataclysmic variables (CVs) and AM CVn binaries jointly selected from SRG/eROSITA eRASS1 and Gaia DR3 using an X-ray + optical color–color diagram (the "X-ray Main Sequence"). This tool identifies all CV subtypes, including magnetic and low-accretion rate systems, in contrast to most previous surveys. We find 23 CVs, 3 of which are AM CVns, out to 150 pc in the Western Galactic Hemisphere. Our 150 pc sample is spectroscopically verified and complete down to LX = 1.3 × 1029 erg s−1 in the 0.2–2.3 keV band, and we also present CV candidates out to 300 pc and 1000 pc. We discovered two previously unknown systems in our 150 pc sample: the third nearest AM CVn and a magnetic period bouncer. We find the mean LX of CVs to be 〈LX〉 ≈ 4.6 × 1030 erg s−1, in contrast to previous surveys which yielded 〈LX〉 ∼ 1031−1032 erg s−1. We construct X-ray luminosity functions that, for the first time, flatten out at LX ∼ 1030 erg s−1. We infer average number, mass, and luminosity densities of ρN,CV = (3.7 ± 0.7) × 10−6pc−3, (math formular), and (math formular), respectively, in the solar neighborhood. Our uniform selection method also allows us to place meaningful estimates on the space density of AM CVns, ρN,AM CVn = (5.5 ± 3.7) × 10−7 pc−3. Magnetic CVs and period bouncers make up 35% and 25% of our sample, respectively. This work, through a novel discovery technique, shows that the observed number densities of CVs and AM CVns, as well as the fraction of period bouncers, are still in tension with population synthesis estimates.' acknowledgement: "We thank Roman Krivonos for insightful feedback, Kevin Burdge, Dovi Poznanski, and Jim Fuller for useful discussions, and Sunny Wong for providing AM CVn evolutionary models. A.C.R. acknowledges support from an NSF Graduate Fellowship.\r\n\r\nA.C.R. thanks the LSST-DA Data Science Fellowship Program, which is funded by LSST-DA, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. RLO is a Research Fellow of the Brazilian institution CNPq (PQ-315632/2023-2).\r\n\r\nThis work is based on data from eROSITA, the soft X-ray instrument aboard SRG, a joint Russian-German science mission supported by the Russian Space Agency (Roskosmos), in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI), and the Deutsches Zentrum für Luft- und Raumfahrt (DLR). The SRG spacecraft was built by Lavochkin Association (NPOL) and its subcontractors, and is operated by NPOL with support from the Max Planck Institute for Extraterrestrial Physics (MPE). The development and construction of the eROSITA X-ray instrument was led by MPE, with contributions from the Dr. Karl Remeis Observatory Bamberg & ECAP (FAU Erlangen-Nuernberg), the University of Hamburg Observatory, the Leibniz Institute for Astrophysics Potsdam (AIP), and the Institute for Astronomy and Astrophysics of the University of Tübingen, with the support of DLR and the Max Planck Society. The Argelander Institute for Astronomy of the University of Bonn and the Ludwig Maximilians Universität Munich also participated in the science preparation for eROSITA.\r\n\r\nThis work presents results from the European Space Agency (ESA) space mission Gaia. Gaia data are being processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC is provided by national institutions, in particular the institutions participating in the Gaia MultiLateral Agreement (MLA). The Gaia mission website is https://www.cosmos.esa.int/gaia. The Gaia archive website is https://archives.esac.esa.int/gaia.\r\n\r\nSome of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We are also grateful to the staff of Palomar Observatory and that of Lick Observatory for their assistance in carrying out observations used in this work.\r\n\r\nBased on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW.\r\n\r\nSoftware: used: Python and the following libraries: matplotlib (Hunter 2007), scipy (Virtanen et al. 2020), astropy (Astropy Collaboration et al. 2013), numpy (van der Walt et al. 2011). PypeIt (Prochaska et al. 2020), lpipe (Perley 2019), and Tool for OPerations on Catalogues And Tables (TOPCAT) (Taylor 2005)." article_number: '014201' article_processing_charge: No article_type: original arxiv: 1 author: - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Valery full_name: Suleimanov, Valery last_name: Suleimanov - first_name: Anna F. full_name: Pala, Anna F. last_name: Pala - first_name: Shrinivas R. full_name: Kulkarni, Shrinivas R. last_name: Kulkarni - first_name: Boris full_name: Gaensicke, Boris last_name: Gaensicke - first_name: Kaya full_name: Mori, Kaya last_name: Mori - first_name: R. Michael full_name: Rich, R. Michael last_name: Rich - first_name: Arnab full_name: Sarkar, Arnab last_name: Sarkar - first_name: Tong full_name: Bao, Tong last_name: Bao - first_name: Raimundo Lopes full_name: De Oliveira, Raimundo Lopes last_name: De Oliveira - first_name: Gavin full_name: Ramsay, Gavin last_name: Ramsay - first_name: Paula full_name: Szkody, Paula last_name: Szkody - first_name: Matthew full_name: Graham, Matthew last_name: Graham - first_name: Thomas A. full_name: Prince, Thomas A. last_name: Prince - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Zachary P. full_name: Vanderbosch, Zachary P. last_name: Vanderbosch - first_name: Jan Van full_name: Roestel, Jan Van last_name: Roestel - first_name: Kaustav K. full_name: Das, Kaustav K. last_name: Das - first_name: Yu Jing full_name: Qin, Yu Jing last_name: Qin - first_name: Mansi M. full_name: Kasliwal, Mansi M. last_name: Kasliwal - first_name: Avery full_name: Wold, Avery last_name: Wold - first_name: Steven L. full_name: Groom, Steven L. last_name: Groom - first_name: Daniel full_name: Reiley, Daniel last_name: Reiley - first_name: Reed full_name: Riddle, Reed last_name: Riddle citation: ama: 'Rodriguez AC, El-Badry K, Suleimanov V, et al. Cataclysmic variables and AM CVn binaries in SRG/eROSITA + Gaia: Volume limited samples, X-ray luminosity functions, and space densities. Publications of the Astronomical Society of the Pacific. 2025;137(1). doi:10.1088/1538-3873/ada185' apa: 'Rodriguez, A. C., El-Badry, K., Suleimanov, V., Pala, A. F., Kulkarni, S. R., Gaensicke, B., … Riddle, R. (2025). Cataclysmic variables and AM CVn binaries in SRG/eROSITA + Gaia: Volume limited samples, X-ray luminosity functions, and space densities. Publications of the Astronomical Society of the Pacific. IOP Publishing. https://doi.org/10.1088/1538-3873/ada185' chicago: 'Rodriguez, Antonio C., Kareem El-Badry, Valery Suleimanov, Anna F. Pala, Shrinivas R. Kulkarni, Boris Gaensicke, Kaya Mori, et al. “Cataclysmic Variables and AM CVn Binaries in SRG/EROSITA + Gaia: Volume Limited Samples, X-Ray Luminosity Functions, and Space Densities.” Publications of the Astronomical Society of the Pacific. IOP Publishing, 2025. https://doi.org/10.1088/1538-3873/ada185.' ieee: 'A. C. Rodriguez et al., “Cataclysmic variables and AM CVn binaries in SRG/eROSITA + Gaia: Volume limited samples, X-ray luminosity functions, and space densities,” Publications of the Astronomical Society of the Pacific, vol. 137, no. 1. IOP Publishing, 2025.' ista: 'Rodriguez AC, El-Badry K, Suleimanov V, Pala AF, Kulkarni SR, Gaensicke B, Mori K, Rich RM, Sarkar A, Bao T, De Oliveira RL, Ramsay G, Szkody P, Graham M, Prince TA, Caiazzo I, Vanderbosch ZP, Roestel JV, Das KK, Qin YJ, Kasliwal MM, Wold A, Groom SL, Reiley D, Riddle R. 2025. Cataclysmic variables and AM CVn binaries in SRG/eROSITA + Gaia: Volume limited samples, X-ray luminosity functions, and space densities. Publications of the Astronomical Society of the Pacific. 137(1), 014201.' mla: 'Rodriguez, Antonio C., et al. “Cataclysmic Variables and AM CVn Binaries in SRG/EROSITA + Gaia: Volume Limited Samples, X-Ray Luminosity Functions, and Space Densities.” Publications of the Astronomical Society of the Pacific, vol. 137, no. 1, 014201, IOP Publishing, 2025, doi:10.1088/1538-3873/ada185.' short: A.C. Rodriguez, K. El-Badry, V. Suleimanov, A.F. Pala, S.R. Kulkarni, B. Gaensicke, K. Mori, R.M. Rich, A. Sarkar, T. Bao, R.L. De Oliveira, G. Ramsay, P. Szkody, M. Graham, T.A. Prince, I. Caiazzo, Z.P. Vanderbosch, J.V. Roestel, K.K. Das, Y.J. Qin, M.M. Kasliwal, A. Wold, S.L. Groom, D. Reiley, R. Riddle, Publications of the Astronomical Society of the Pacific 137 (2025). date_created: 2025-01-19T23:01:51Z date_published: 2025-01-01T00:00:00Z date_updated: 2025-02-27T12:46:32Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1088/1538-3873/ada185 external_id: arxiv: - '2408.16053' isi: - '001393204700001' file: - access_level: open_access checksum: 02a9be04a6704fc272ed5a976e5fa8c5 content_type: application/pdf creator: dernst date_created: 2025-01-20T09:52:34Z date_updated: 2025-01-20T09:52:34Z file_id: '18860' file_name: 2025_PASP_Rodriguez.pdf file_size: 5155631 relation: main_file success: 1 file_date_updated: 2025-01-20T09:52:34Z has_accepted_license: '1' intvolume: ' 137' isi: 1 issue: '1' language: - iso: eng month: '01' oa: 1 oa_version: Published Version publication: Publications of the Astronomical Society of the Pacific publication_identifier: issn: - 0004-6280 publication_status: published publisher: IOP Publishing quality_controlled: '1' scopus_import: '1' status: public title: 'Cataclysmic variables and AM CVn binaries in SRG/eROSITA + Gaia: Volume limited samples, X-ray luminosity functions, and space densities' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/3.0/legalcode name: Creative Commons Attribution 3.0 Unported (CC BY 3.0) short: CC BY (3.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 137 year: '2025' ... --- OA_place: publisher OA_type: diamond _id: '18852' abstract: - lang: eng text: 'Recent observations have found a growing number of hypervelocity stars with speeds of ≈1500 − 2500 km s−1 that could have only been produced through thermonuclear supernovae in white dwarf binaries. Most of the observed hypervelocity runaways in this class display a surprising inflated structure: their current radii are roughly an order of magnitude greater than they would have been as white dwarfs filling their Roche lobe. While many simulations exist studying the dynamical phase leading to supernova detonation in these systems, no detailed calculations of the long-term structure of the runaways have yet been performed. We used an existing AREPO hydrodynamical simulation of a supernova in a white dwarf binary as a starting point for the evolution of these stars with the one-dimensional stellar evolution code MESA. We show that the supernova shock is not energetic enough to inflate the white dwarf over timescales longer than a few thousand years, significantly shorter than the 105 − 6 year lifetimes inferred for observed hypervelocity runaways. Although they experience a shock from a supernova less than ≈0.02 R⊙ away, our models do not experience significant interior heating, and all contract back to radii of around 0.01 R⊙ within about 104 years. Explaining the observed inflated states requires either an additional source of significant heating or some other physics that is not yet accounted for in the subsequent evolution.' acknowledgement: 'This project was originally started as part of the Kavli Summer Program which took place in the Max Planck Institute for Astrophysics in Garching in July 2023, supported by the Kavli Foundation. We are grateful to Stephen Justham, Selma de Mink, and Jim Fuller for enriching discussions. We would like to thank the anonymous referee for their helpful report. A.B. was supported by the Deutsche Forschungsgemeinschaft (DFG) through grant GE2506/18-1. K.J.S. was supported by NASA through the Astrophysics Theory Program (80NSSC20K0544) and by NASA/ESA Hubble Space Telescope programs #15871 and #15918. W.E.K. was supported by NSF Grants OAC-2311323, AST-2206523, and NASA/ESA HST-AR-Theory HSTAR-16613.002-A. K.E. was supported in part by HST-GO-17441.001-A. AB and ASR would like to thank Rob Farmer for his support with PyMESA.' article_number: A114 article_processing_charge: No article_type: original arxiv: 1 author: - first_name: Aakash full_name: Bhat, Aakash last_name: Bhat - first_name: Evan B. full_name: Bauer, Evan B. last_name: Bauer - first_name: Rüdiger full_name: Pakmor, Rüdiger last_name: Pakmor - first_name: Ken J. full_name: Shen, Ken J. last_name: Shen - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Abinaya Swaruba full_name: Rajamuthukumar, Abinaya Swaruba last_name: Rajamuthukumar - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Wolfgang E. full_name: Kerzendorf, Wolfgang E. last_name: Kerzendorf citation: ama: Bhat A, Bauer EB, Pakmor R, et al. Supernova shocks cannot explain the inflated state of hypervelocity runaways from white dwarf binaries. Astronomy & Astrophysics. 2025;693(1). doi:10.1051/0004-6361/202451371 apa: Bhat, A., Bauer, E. B., Pakmor, R., Shen, K. J., Caiazzo, I., Rajamuthukumar, A. S., … Kerzendorf, W. E. (2025). Supernova shocks cannot explain the inflated state of hypervelocity runaways from white dwarf binaries. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/202451371 chicago: Bhat, Aakash, Evan B. Bauer, Rüdiger Pakmor, Ken J. Shen, Ilaria Caiazzo, Abinaya Swaruba Rajamuthukumar, Kareem El-Badry, and Wolfgang E. Kerzendorf. “Supernova Shocks Cannot Explain the Inflated State of Hypervelocity Runaways from White Dwarf Binaries.” Astronomy & Astrophysics. EDP Sciences, 2025. https://doi.org/10.1051/0004-6361/202451371. ieee: A. Bhat et al., “Supernova shocks cannot explain the inflated state of hypervelocity runaways from white dwarf binaries,” Astronomy & Astrophysics, vol. 693, no. 1. EDP Sciences, 2025. ista: Bhat A, Bauer EB, Pakmor R, Shen KJ, Caiazzo I, Rajamuthukumar AS, El-Badry K, Kerzendorf WE. 2025. Supernova shocks cannot explain the inflated state of hypervelocity runaways from white dwarf binaries. Astronomy & Astrophysics. 693(1), A114. mla: Bhat, Aakash, et al. “Supernova Shocks Cannot Explain the Inflated State of Hypervelocity Runaways from White Dwarf Binaries.” Astronomy & Astrophysics, vol. 693, no. 1, A114, EDP Sciences, 2025, doi:10.1051/0004-6361/202451371. short: A. Bhat, E.B. Bauer, R. Pakmor, K.J. Shen, I. Caiazzo, A.S. Rajamuthukumar, K. El-Badry, W.E. Kerzendorf, Astronomy & Astrophysics 693 (2025). date_created: 2025-01-19T23:01:51Z date_published: 2025-01-07T00:00:00Z date_updated: 2026-02-16T12:08:05Z day: '07' ddc: - '520' department: - _id: IlCa doi: 10.1051/0004-6361/202451371 external_id: arxiv: - '2407.03424' isi: - '001406577300001' file: - access_level: open_access checksum: e532b9c8123c29cfb0ee758e6d00453c content_type: application/pdf creator: dernst date_created: 2025-01-20T09:57:00Z date_updated: 2025-01-20T09:57:00Z file_id: '18861' file_name: 2025_AstronomyAstrophysics_Bhat.pdf file_size: 1692527 relation: main_file success: 1 file_date_updated: 2025-01-20T09:57:00Z has_accepted_license: '1' intvolume: ' 693' isi: 1 issue: '1' language: - iso: eng month: '01' oa: 1 oa_version: Published Version publication: Astronomy & Astrophysics publication_identifier: eissn: - 1432-0746 issn: - 0004-6361 publication_status: published publisher: EDP Sciences quality_controlled: '1' scopus_import: '1' status: public title: Supernova shocks cannot explain the inflated state of hypervelocity runaways from white dwarf binaries tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 693 year: '2025' ... --- OA_place: publisher OA_type: diamond _id: '18866' abstract: - lang: eng text: Using JWST Near Infrared Camera (NIRCam) images of the globular cluster 47,Tucanæ, (or NGC,104), taken at two epochs just 7 months apart, we derived proper-motion membership down to F322W2 ∼ 27. We identified an intriguing feature at the very low-mass end of the main sequence, around ∼ 0.08,M_⋅, at magnitudes F322W2 ∼ 24 and m_ F150W2 ∼ 25. This feature, dubbed 'kink', is characterized by a prominent discontinuity in the slope of the main sequence. A similar discontinuity is seen in theoretical isochrones with oxygen-poor chemistries, related to the rapid onset of absorption. We therefore hypothesize that the cluster hosts disproportionately more oxygen-poor stars near the bottom of the main sequence compared to the upper main sequence and the red giant branch. Our results show no strong or conclusive evidence of a rise in the brown dwarf luminosity function at faint magnitudes, in contrast to previous findings likely affected by faint red background galaxies. In our analysis, we accounted for this contamination by using proper motion membership. acknowledgement: We dedicate this paper to the memory of our colleague Prof. Harvey Richer (⋆ April 1944 —† 13 November 2023), a highly accomplished astronomer and expert in stellar populations and in particular within globular clusters, who passed away during this project. Harvey grew up in Montreal and was at least the second star man to graduate from his high school, having been preceded by William Shatner by more than a decade. He worked at the University of British Columbia for most of his career, and his focus was the late stages of stellar evolution, in particular carbon stars and white dwarfs. We thank the referee for his valuable suggestions and comments, which helped improve the paper, as well as for his prompt revision. article_number: A68 article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: M. full_name: Scalco, M. last_name: Scalco - first_name: R. full_name: Gerasimov, R. last_name: Gerasimov - first_name: L. R. full_name: Bedin, L. R. last_name: Bedin - first_name: E. full_name: Vesperini, E. last_name: Vesperini - first_name: M. full_name: Correnti, M. last_name: Correnti - first_name: D. full_name: Nardiello, D. last_name: Nardiello - first_name: A. full_name: Burgasser, A. last_name: Burgasser - first_name: H. full_name: Richer, H. last_name: Richer - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: J. full_name: Heyl, J. last_name: Heyl - first_name: M. full_name: Libralato, M. last_name: Libralato - first_name: J. full_name: Anderson, J. last_name: Anderson - first_name: M. full_name: Griggio, M. last_name: Griggio citation: ama: Scalco M, Gerasimov R, Bedin LR, et al. JWST photometry and astrometry of 47 Tucanae. Discontinuity in the stellar sequence at the star--brown dwarf transition. Astronomy & Astrophysics. 2025;694. doi:10.1051/0004-6361/202452907 apa: Scalco, M., Gerasimov, R., Bedin, L. R., Vesperini, E., Correnti, M., Nardiello, D., … Griggio, M. (2025). JWST photometry and astrometry of 47 Tucanae. Discontinuity in the stellar sequence at the star--brown dwarf transition. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/202452907 chicago: Scalco, M., R. Gerasimov, L. R. Bedin, E. Vesperini, M. Correnti, D. Nardiello, A. Burgasser, et al. “JWST Photometry and Astrometry of 47 Tucanae. Discontinuity in the Stellar Sequence at the Star--Brown Dwarf Transition.” Astronomy & Astrophysics. EDP Sciences, 2025. https://doi.org/10.1051/0004-6361/202452907. ieee: M. Scalco et al., “JWST photometry and astrometry of 47 Tucanae. Discontinuity in the stellar sequence at the star--brown dwarf transition,” Astronomy & Astrophysics, vol. 694. EDP Sciences, 2025. ista: Scalco M, Gerasimov R, Bedin LR, Vesperini E, Correnti M, Nardiello D, Burgasser A, Richer H, Caiazzo I, Heyl J, Libralato M, Anderson J, Griggio M. 2025. JWST photometry and astrometry of 47 Tucanae. Discontinuity in the stellar sequence at the star--brown dwarf transition. Astronomy & Astrophysics. 694, A68. mla: Scalco, M., et al. “JWST Photometry and Astrometry of 47 Tucanae. Discontinuity in the Stellar Sequence at the Star--Brown Dwarf Transition.” Astronomy & Astrophysics, vol. 694, A68, EDP Sciences, 2025, doi:10.1051/0004-6361/202452907. short: M. Scalco, R. Gerasimov, L.R. Bedin, E. Vesperini, M. Correnti, D. Nardiello, A. Burgasser, H. Richer, I. Caiazzo, J. Heyl, M. Libralato, J. Anderson, M. Griggio, Astronomy & Astrophysics 694 (2025). date_created: 2025-01-21T15:29:36Z date_published: 2025-02-04T00:00:00Z date_updated: 2025-07-10T11:51:28Z day: '04' ddc: - '520' department: - _id: IlCa doi: 10.1051/0004-6361/202452907 external_id: arxiv: - '2501.04446' isi: - '001414753300007' file: - access_level: open_access checksum: db765ce222df60a1e7c19da1968906a8 content_type: application/pdf creator: dernst date_created: 2025-04-16T07:13:31Z date_updated: 2025-04-16T07:13:31Z file_id: '19569' file_name: 2025_AstronomyAstrophysics_Scalco.pdf file_size: 18080704 relation: main_file success: 1 file_date_updated: 2025-04-16T07:13:31Z has_accepted_license: '1' intvolume: ' 694' isi: 1 language: - iso: eng month: '02' oa: 1 oa_version: Published Version publication: Astronomy & Astrophysics publication_identifier: eissn: - 1432-0746 issn: - 0004-6361 publication_status: published publisher: EDP Sciences quality_controlled: '1' scopus_import: '1' status: public title: JWST photometry and astrometry of 47 Tucanae. Discontinuity in the stellar sequence at the star--brown dwarf transition tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 694 year: '2025' ... --- OA_place: publisher OA_type: hybrid _id: '19439' abstract: - lang: eng text: "White dwarfs (WDs) are the most abundant compact objects, and recent surveys have suggested that over a third of WDs in accreting binaries host a strong (B \ ≳ 1 MG) magnetic field. However, the origin and evolution of WD magnetism remain under debate. Two WD pulsars, AR Sco and J191213.72–441045.1 (J1912), have been found, which are non-accreting binaries hosting rapidly spinning (1.97 minutes and 5.30 minutes, respectively) magnetic WDs. The WD in AR Sco is slowing down on a (math formular) yr timescale. It is believed they will eventually become polars, accreting systems in which a magnetic WD (B ≈ 10−240 MG) accretes from a Roche lobe-filling donor spinning in sync with the orbit (≳78 minutes). Here, we present multiwavelength data and analysis of Gaia22ayj, which outbursted in 2022 March. We find that Gaia22ayj is a magnetic accreting WD that is rapidly spinning down (math formular\r\n yr) like WD pulsars, but shows clear evidence of accretion, like polars. Strong linear polarization (40%) is detected in Gaia22ayj; such high levels have only been seen in the WD pulsar AR Sco and demonstrate the WD is magnetic. High speed photometry reveals a 9.36 minutes period accompanying a high amplitude (∼2 mag) modulation. We associate this with a WD spin or spin–orbit beat period, not an orbital period as was previously suggested. Fast (60 s) optical spectroscopy reveals a broad \"hump,\" reminiscent of cyclotron emission in polars, between 4000 and 8000 Å. We find an X-ray luminosity of (math formular) in the 0.3–8 keV energy range, while two very large array radio campaigns resulted in a non-detection with a Fr < 15.8 μJy 3σ upper limit. The shared properties of both WD pulsars and polars suggest that Gaia22ayj is a missing link between the two classes of magnetic WD binaries." acknowledgement: "We wish to dedicate this work to the memory of our colleague and friend Tom Marsh. Tom's enthusiasm to work on this object and rapid efforts to facilitate data collection truly made this project possible.\r\n\r\nA.C.R. acknowledges support from an NSF Graduate Fellowship. A.C.R. thanks the LSST-DA Data Science Fellowship Program, which is funded by LSST-DA, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. P.R.-G. acknowledges support by the Spanish Agencia Estatal de Investigación del Ministerio de Ciencia e Innovación (MCIN/AEI) and the European Regional Development Fund (ERDF) under grant PID2021–124879NB–I00. M.R.S. is supported by FONDECYT (grant No. 1221059) and eRO-STEP (SA 2131/15-2 project number 414059771). I.P. acknowledges support from a Royal Society University Research Fellowship (URF/R1/231496). We thank the referee for feedback that improved the clarity of this paper.\r\n\r\nBased on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofìsica de Canarias, on the island of La Palma. Based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the ZTF project. ZTF is supported by the National Science Foundation under grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW.\r\n\r\nSome of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We are also grateful to the staff of Palomar Observatory for their assistance in carrying out observations used in this work.\r\n\r\nPartly based on observations made with the NOT, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The data presented here were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT. The observation with the SALT was obtained under program 2021-2-LSP-001 (PI: D. Buckley). Polish participation in SALT is funded by grant No. MEiN nr 2021/WK/01. D.A.H.B. acknowledges support from the National Research Foundation.\r\n\r\nThis work presents results from the European Space Agency (ESA) space mission Gaia. Gaia data are being processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC is provided by national institutions, in particular the institutions participating in the Gaia MultiLateral Agreement (MLA). The Gaia mission website is https://www.cosmos.esa.int/gaia. The Gaia archive website is https://archives.esac.esa.int/gaia. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester\r\n\r\nE.C.B. and J.K. acknowledge support from the DIRAC Institute in the Department of Astronomy at the University of Washington. The DIRAC Institute is supported through generous gifts from the Charles and Lisa Simonyi Fund for Arts and Sciences, and the Washington Research Foundation." article_number: '024202' article_processing_charge: Yes (in subscription journal) article_type: original arxiv: 1 author: - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Pasi full_name: Hakala, Pasi last_name: Hakala - first_name: Pablo full_name: Rodríguez-Gil, Pablo last_name: Rodríguez-Gil - first_name: Tong full_name: Bao, Tong last_name: Bao - first_name: Ilkham full_name: Galiullin, Ilkham last_name: Galiullin - first_name: Jacob A. full_name: Kurlander, Jacob A. last_name: Kurlander - first_name: Casey J. full_name: Law, Casey J. last_name: Law - first_name: Ingrid full_name: Pelisoli, Ingrid last_name: Pelisoli - first_name: Matthias R. full_name: Schreiber, Matthias R. last_name: Schreiber - first_name: Kevin full_name: Burdge, Kevin last_name: Burdge - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Jan Van full_name: Roestel, Jan Van last_name: Roestel - first_name: Paula full_name: Szkody, Paula last_name: Szkody - first_name: Andrew J. full_name: Drake, Andrew J. last_name: Drake - first_name: David A.H. full_name: Buckley, David A.H. last_name: Buckley - first_name: Stephen B. full_name: Potter, Stephen B. last_name: Potter - first_name: Boris full_name: Gaensicke, Boris last_name: Gaensicke - first_name: Kaya full_name: Mori, Kaya last_name: Mori - first_name: Eric C. full_name: Bellm, Eric C. last_name: Bellm - first_name: Shrinivas R. full_name: Kulkarni, Shrinivas R. last_name: Kulkarni - first_name: Thomas A. full_name: Prince, Thomas A. last_name: Prince - first_name: Matthew full_name: Graham, Matthew last_name: Graham - first_name: Mansi M. full_name: Kasliwal, Mansi M. last_name: Kasliwal - first_name: Sam full_name: Rose, Sam last_name: Rose - first_name: Yashvi full_name: Sharma, Yashvi last_name: Sharma - first_name: Tomás full_name: Ahumada, Tomás last_name: Ahumada - first_name: Shreya full_name: Anand, Shreya last_name: Anand - first_name: Akke full_name: Viitanen, Akke last_name: Viitanen - first_name: Avery full_name: Wold, Avery last_name: Wold - first_name: Tracy X. full_name: Chen, Tracy X. last_name: Chen - first_name: Reed full_name: Riddle, Reed last_name: Riddle - first_name: Roger full_name: Smith, Roger last_name: Smith citation: ama: 'Rodriguez AC, El-Badry K, Hakala P, et al. A link between White Dwarf pulsars and polars: Multiwavelength observations of the 9.36-minute period variable Gaia22ayj. Publications of the Astronomical Society of the Pacific. 2025;137(2). doi:10.1088/1538-3873/adb0f1' apa: 'Rodriguez, A. C., El-Badry, K., Hakala, P., Rodríguez-Gil, P., Bao, T., Galiullin, I., … Smith, R. (2025). A link between White Dwarf pulsars and polars: Multiwavelength observations of the 9.36-minute period variable Gaia22ayj. Publications of the Astronomical Society of the Pacific. IOP Publishing. https://doi.org/10.1088/1538-3873/adb0f1' chicago: 'Rodriguez, Antonio C., Kareem El-Badry, Pasi Hakala, Pablo Rodríguez-Gil, Tong Bao, Ilkham Galiullin, Jacob A. Kurlander, et al. “A Link between White Dwarf Pulsars and Polars: Multiwavelength Observations of the 9.36-Minute Period Variable Gaia22ayj.” Publications of the Astronomical Society of the Pacific. IOP Publishing, 2025. https://doi.org/10.1088/1538-3873/adb0f1.' ieee: 'A. C. Rodriguez et al., “A link between White Dwarf pulsars and polars: Multiwavelength observations of the 9.36-minute period variable Gaia22ayj,” Publications of the Astronomical Society of the Pacific, vol. 137, no. 2. IOP Publishing, 2025.' ista: 'Rodriguez AC, El-Badry K, Hakala P, Rodríguez-Gil P, Bao T, Galiullin I, Kurlander JA, Law CJ, Pelisoli I, Schreiber MR, Burdge K, Caiazzo I, Roestel JV, Szkody P, Drake AJ, Buckley DAH, Potter SB, Gaensicke B, Mori K, Bellm EC, Kulkarni SR, Prince TA, Graham M, Kasliwal MM, Rose S, Sharma Y, Ahumada T, Anand S, Viitanen A, Wold A, Chen TX, Riddle R, Smith R. 2025. A link between White Dwarf pulsars and polars: Multiwavelength observations of the 9.36-minute period variable Gaia22ayj. Publications of the Astronomical Society of the Pacific. 137(2), 024202.' mla: 'Rodriguez, Antonio C., et al. “A Link between White Dwarf Pulsars and Polars: Multiwavelength Observations of the 9.36-Minute Period Variable Gaia22ayj.” Publications of the Astronomical Society of the Pacific, vol. 137, no. 2, 024202, IOP Publishing, 2025, doi:10.1088/1538-3873/adb0f1.' short: A.C. Rodriguez, K. El-Badry, P. Hakala, P. Rodríguez-Gil, T. Bao, I. Galiullin, J.A. Kurlander, C.J. Law, I. Pelisoli, M.R. Schreiber, K. Burdge, I. Caiazzo, J.V. Roestel, P. Szkody, A.J. Drake, D.A.H. Buckley, S.B. Potter, B. Gaensicke, K. Mori, E.C. Bellm, S.R. Kulkarni, T.A. Prince, M. Graham, M.M. Kasliwal, S. Rose, Y. Sharma, T. Ahumada, S. Anand, A. Viitanen, A. Wold, T.X. Chen, R. Riddle, R. Smith, Publications of the Astronomical Society of the Pacific 137 (2025). date_created: 2025-03-23T23:01:26Z date_published: 2025-02-01T00:00:00Z date_updated: 2025-09-30T11:15:10Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1088/1538-3873/adb0f1 external_id: arxiv: - '2501.01490' isi: - '001427877700001' file: - access_level: open_access checksum: 42d5aa504479c3fdf2a10165a9e3319f content_type: application/pdf creator: dernst date_created: 2025-03-25T10:01:24Z date_updated: 2025-03-25T10:01:24Z file_id: '19455' file_name: 2025_PubAstronomSocPacific_Rodriguez.pdf file_size: 3291933 relation: main_file success: 1 file_date_updated: 2025-03-25T10:01:24Z has_accepted_license: '1' intvolume: ' 137' isi: 1 issue: '2' language: - iso: eng month: '02' oa: 1 oa_version: Published Version publication: Publications of the Astronomical Society of the Pacific publication_identifier: issn: - 0004-6280 publication_status: published publisher: IOP Publishing quality_controlled: '1' scopus_import: '1' status: public title: 'A link between White Dwarf pulsars and polars: Multiwavelength observations of the 9.36-minute period variable Gaia22ayj' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345 volume: 137 year: '2025' ... --- OA_place: publisher OA_type: gold _id: '19840' abstract: - lang: eng text: "We report the discovery of two new magnetic cataclysmic variables with brown dwarf companions and long orbital periods (P_{\\rm orb}=95\\pm1 and 104\\pm2 min). This discovery increases the sample of candidate magnetic period bouncers with confirmed sub-stellar donors from four to six. We also find their X-ray luminosity from archival XMM–Newton observations to be in the range L_{\\rm X}\\approx10^{28}-10^{29} \\mathrm{erg\\,s^{-1}} in the 0.25–10 keV band. This low luminosity is comparable with the other candidates, and at least an order of magnitude lower than the X-ray luminosities typically measured in cataclysmic variables. The X-ray fluxes imply mass transfer rates that are much lower than predicted by evolutionary models, even if some of the discrepancy is due to the accretion energy being emitted in other bands, such as via cyclotron emission at infrared wavelengths. Although it is possible that some or all of these systems formed directly as binaries containing a brown dwarf, it is likely that the donor used to be a low-mass star and that the systems followed the evolutionary track for cataclysmic variables, evolving past the period bounce. The donor in long period systems is expected to be a low-mass, cold brown dwarf. This hypothesis is supported by near-infrared photometric observations that constrain the donors in the two systems to be brown dwarfs cooler than \r\n1100 K (spectral types T5 or later), most likely losing mass via Roche Lobe overflow or winds. The serendipitous discovery of two magnetic period bouncers in the small footprint of the XMM–Newton catalogue implies a large space density of these type of systems, possibly compatible with the prediction of 40–70 per cent of magnetic cataclysmic variables to be period bouncers." acknowledgement: "We thank Matthias Schreiber for his insightful comments. Support for this work was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51527.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Support for this work was provided by NASA through Chandra Award Number GO4-25014X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. IC was also supported by NASA through grants from the Space Telescope Science Institute, under NASA contracts NASA.22K1813, NAS5-26555, and NAS5-03127. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 101020057). This research was supported in part by grant NSF PHY-1748958 to the Kavli Institute for Theoretical Physics (KITP). PJW acknowledges support from the UK Science and Technology Facilities Council (STFC) through consolidated grants ST/T000406/1 and ST/X001121/1. RA was supported by NASA through the NASA Hubble Fellowship grant #HST-HF2-51499.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.\r\n\r\nThis research has made use of data obtained from the 4XMM XMM–Newton Serendipitous Source Catalogue compiled by the 10 institutes of the XMM–Newton Survey Science Centre selected by ESA. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard–Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant no. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation grant no. AST–1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. This work is based in part on data obtained as part of the UKIDSS. This research made use of hips2fits,4 a service provided by CDS, and of astropy (Astropy Collaboration 2013)." article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Tim full_name: Cunningham, Tim last_name: Cunningham - first_name: Ilaria full_name: Caiazzo, Ilaria id: 8ae5b6e7-2a03-11ee-914d-b58ed7a3b47d last_name: Caiazzo orcid: 0000-0002-4770-5388 - first_name: Gracjan full_name: Sienkiewicz, Gracjan last_name: Sienkiewicz - first_name: Peter J. full_name: Wheatley, Peter J. last_name: Wheatley - first_name: Boris T. full_name: Gänsicke, Boris T. last_name: Gänsicke - first_name: Kareem full_name: El-Badry, Kareem last_name: El-Badry - first_name: Riccardo full_name: Arcodia, Riccardo last_name: Arcodia - first_name: David full_name: Charbonneau, David last_name: Charbonneau - first_name: Liam full_name: Connor, Liam last_name: Connor - first_name: Kishalay full_name: De, Kishalay last_name: De - first_name: Pasi full_name: Hakala, Pasi last_name: Hakala - first_name: Scott J. full_name: Kenyon, Scott J. last_name: Kenyon - first_name: Sumit Kumar full_name: Maheshwari, Sumit Kumar last_name: Maheshwari - first_name: Antonio C. full_name: Rodriguez, Antonio C. last_name: Rodriguez - first_name: Jan full_name: Van Roestel, Jan last_name: Van Roestel - first_name: Pier Emmanuel full_name: Tremblay, Pier Emmanuel last_name: Tremblay citation: ama: Cunningham T, Caiazzo I, Sienkiewicz G, et al. Discovery of two new polars evolved past the period bounce. Monthly Notices of the Royal Astronomical Society. 2025;540(1):633-649. doi:10.1093/mnras/staf561 apa: Cunningham, T., Caiazzo, I., Sienkiewicz, G., Wheatley, P. J., Gänsicke, B. T., El-Badry, K., … Tremblay, P. E. (2025). Discovery of two new polars evolved past the period bounce. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/staf561 chicago: Cunningham, Tim, Ilaria Caiazzo, Gracjan Sienkiewicz, Peter J. Wheatley, Boris T. Gänsicke, Kareem El-Badry, Riccardo Arcodia, et al. “Discovery of Two New Polars Evolved Past the Period Bounce.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2025. https://doi.org/10.1093/mnras/staf561. ieee: T. Cunningham et al., “Discovery of two new polars evolved past the period bounce,” Monthly Notices of the Royal Astronomical Society, vol. 540, no. 1. Oxford University Press, pp. 633–649, 2025. ista: Cunningham T, Caiazzo I, Sienkiewicz G, Wheatley PJ, Gänsicke BT, El-Badry K, Arcodia R, Charbonneau D, Connor L, De K, Hakala P, Kenyon SJ, Maheshwari SK, Rodriguez AC, Van Roestel J, Tremblay PE. 2025. Discovery of two new polars evolved past the period bounce. Monthly Notices of the Royal Astronomical Society. 540(1), 633–649. mla: Cunningham, Tim, et al. “Discovery of Two New Polars Evolved Past the Period Bounce.” Monthly Notices of the Royal Astronomical Society, vol. 540, no. 1, Oxford University Press, 2025, pp. 633–49, doi:10.1093/mnras/staf561. short: T. Cunningham, I. Caiazzo, G. Sienkiewicz, P.J. Wheatley, B.T. Gänsicke, K. El-Badry, R. Arcodia, D. Charbonneau, L. Connor, K. De, P. Hakala, S.J. Kenyon, S.K. Maheshwari, A.C. Rodriguez, J. Van Roestel, P.E. Tremblay, Monthly Notices of the Royal Astronomical Society 540 (2025) 633–649. date_created: 2025-06-15T22:01:29Z date_published: 2025-06-01T00:00:00Z date_updated: 2025-09-30T12:50:33Z day: '01' ddc: - '520' department: - _id: IlCa doi: 10.1093/mnras/staf561 external_id: arxiv: - '2503.12675' isi: - '001493143700001' file: - access_level: open_access checksum: 5e675d3696c222e919d6916bad194b01 content_type: application/pdf creator: dernst date_created: 2025-06-23T07:28:36Z date_updated: 2025-06-23T07:28:36Z file_id: '19864' file_name: 2025_MonthlyNoticesRAS_Cunningham.pdf file_size: 3212636 relation: main_file success: 1 file_date_updated: 2025-06-23T07:28:36Z has_accepted_license: '1' intvolume: ' 540' isi: 1 issue: '1' language: - iso: eng month: '06' oa: 1 oa_version: Published Version page: 633-649 publication: Monthly Notices of the Royal Astronomical Society publication_identifier: eissn: - 1365-2966 issn: - 0035-8711 publication_status: published publisher: Oxford University Press quality_controlled: '1' scopus_import: '1' status: public title: Discovery of two new polars evolved past the period bounce tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345 volume: 540 year: '2025' ...