---
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. <i>Astronomy and
    Astrophysics</i>. 2026;706. doi:<a href="https://doi.org/10.1051/0004-6361/202557568">10.1051/0004-6361/202557568</a>'
  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. <i>Astronomy and Astrophysics</i>.
    EDP Sciences. <a href="https://doi.org/10.1051/0004-6361/202557568">https://doi.org/10.1051/0004-6361/202557568</a>'
  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.” <i>Astronomy and Astrophysics</i>.
    EDP Sciences, 2026. <a href="https://doi.org/10.1051/0004-6361/202557568">https://doi.org/10.1051/0004-6361/202557568</a>.'
  ieee: 'W. Yu <i>et al.</i>, “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,” <i>Astronomy and Astrophysics</i>,
    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 and 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.” <i>Astronomy and Astrophysics</i>,
    vol. 706, A14, EDP Sciences, 2026, doi:<a href="https://doi.org/10.1051/0004-6361/202557568">10.1051/0004-6361/202557568</a>.'
  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 and Astrophysics 706 (2026).
date_created: 2026-02-08T23:02:49Z
date_published: 2026-02-01T00:00:00Z
date_updated: 2026-02-16T09:36:24Z
day: '01'
ddc:
- '520'
department:
- _id: IlCa
doi: 10.1051/0004-6361/202557568
external_id:
  arxiv:
  - '2512.04147'
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has_accepted_license: '1'
intvolume: '       706'
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
publication: Astronomy and 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
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  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
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type: journal_article
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volume: 706
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