---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '22960'
abstract:
- lang: eng
  text: "We construct and characterize a sample of 146 little red dots (LRDs) across
    2.0<z<9.3, selecting all sources with v-shaped\r\nultraviolet (UV)–optical continua
    from James Webb Space Telescope (JWST) NIRSpec/PRISM spectra and compact morphologies
    in NIRCam/F444W imaging. We show that LRD continuum spectra are well described
    by modified blackbodies\r\nacross ∼ 0.4 − 1.0 µm, with typical T ∼ 5000 K (λpeak
    ∼ 0.65 µm) across 2 dex in luminosity, and a tail toward T ∼ 2000 K.\r\nLRDs therefore
    trace a locus in the Hertzsprung–Russell diagram that is analogous to stars on
    the Hayashi track, strongly\r\nsupporting the picture that LRDs are active galactic
    nucleus (AGN) embedded in optically thick dense gas envelopes.\r\nHotter LRDs
    with λpeak < 0.65 µm typically have strong Balmer breaks, redder UV slopes, and
    high optical luminosities;\r\nother LRDs show weak or no Balmer breaks, and wide
    variety in βUV and L5100. Crucially, we demonstrate that the UV–\r\noptical continua
    are strongly linked to the Hα, Hβ, [O iii], and O i line properties. There is
    a tight linear relation between\r\nthe Hα and optical continuum luminosities,
    as well as Hα and O i λ8446, indicating that Balmer, O i, and optical emission\r\nmust
    primarily be powered by the same source. The Balmer decrement increases strongly
    toward higher LHα, L5100, and\r\nBalmer break strength, providing key evidence
    for luminosity-dependent effects of collisional (de-)excitation and resonant\r\nscattering
    in the gaseous envelopes. In contrast, we show that [O iii] emission likely originates
    from star-forming host\r\ngalaxies, with strong variation in the AGN-to-host ratio
    among the LRD population. Our work presents an empirical\r\ndescription of the
    nature and structure of LRDs, defining a new benchmark for ongoing LRD model developments."
acknowledgement: "AdG thanks Devesh Nandal for discussions on the properties\r\nof
  convective envelopes and Hayashi limit, and the students of\r\nthe I-HOW JWST Workshop
  (Barbora Adamcova, Biswaraj Palit,\r\nOlena Pastoven, and Weronika Puchalska) for
  their help in producing an early version of Figs 8 and 10. This work is based on\r\nobservations
  made with the NASA/ESA/CSA James Webb Space\r\nTelescope. The data were obtained
  from the Mikulski Archive for\r\nSpace Telescopes at the Space Telescope Science
  Institute, which\r\nis operated by the Association of Universities for Research
  in\r\nAstronomy, Inc., under NASA contract NAS 5-03127 for JWST.\r\nThese observations
  are associated with programs 1180, 1181,\r\n1208, 1212, 1213, 1215, 1286, 1345,
  1433, 2198, 2561, 2750, 2767,\r\n4106, 4233, 5105, 5224, 6368, and 6585. Support
  for program no.\r\n4233 was provided by NASA through a grant from the Space\r\nTelescope
  Science Institute, which is operated by the Association\r\nof Universities for Research
  in Astronomy, Inc., under NASA\r\ncontract NAS 5-03127.\r\nAdG acknowledges support
  from a Clay Fellowship awarded by\r\nthe Smithsonian Astrophysical Observatory.
  REH acknowledges\r\nsupport by the German Aerospace Center (DLR) and the Federal\r\nMinistry
  for Economic Affairs and Energy (BMWi) through program 50OR2403 ‘RUBIES’. The Cosmic
  Dawn Centerisfunded by\r\nthe Danish National Research Foundation (DNRF) under grant\r\nno.
  140. This work has received funding from the Swiss State\r\nSecretariat for Education,
  Research and Innovation (SERI) under\r\ncontract no. MB22.00072, as well as from
  the Swiss National Science Foundation (SNSF) through project grant 200020_207349.\r\nTBM
  was supported by a CIERA fellowship. PD warmly acknowledges support from an NSERC
  discovery grant (RGPIN-2025-\r\n06182). KG acknowledges support from Australian
  Research\r\nCouncil Laureate Fellowship FL180100060. LAB acknowledges\r\nsupport
  from the Dutch Research Council (NWO) under grant\r\nVI.Veni.242.055 (https://doi.org/10.61686/LAJVP77714)
  and the\r\nERC Consolidator grant 101088676 (‘VOYAJ’). YF is supported by\r\nJSPS
  KAKENHI grant nos JP22K21349 and JP23K13149."
article_number: stag1567
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Anna
  full_name: de Graaff, Anna
  last_name: de Graaff
- first_name: Raphael E
  full_name: Hviding, Raphael E
  last_name: Hviding
- first_name: Rohan P
  full_name: Naidu, Rohan P
  last_name: Naidu
- first_name: Jenny E
  full_name: Greene, Jenny E
  last_name: Greene
- first_name: Tim B
  full_name: Miller, Tim B
  last_name: Miller
- first_name: Joel
  full_name: Leja, Joel
  last_name: Leja
- 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: Gabriel
  full_name: Brammer, Gabriel
  last_name: Brammer
- first_name: Harley
  full_name: Katz, Harley
  last_name: Katz
- first_name: Rachel
  full_name: Bezanson, Rachel
  last_name: Bezanson
- first_name: Leindert A
  full_name: Boogaard, Leindert A
  last_name: Boogaard
- first_name: Sownak
  full_name: Bose, Sownak
  last_name: Bose
- first_name: John
  full_name: Chisholm, John
  last_name: Chisholm
- first_name: Nikko J
  full_name: Cleri, Nikko J
  last_name: Cleri
- first_name: Pratika
  full_name: Dayal, Pratika
  last_name: Dayal
- first_name: Robert
  full_name: Feldmann, Robert
  last_name: Feldmann
- first_name: Yoshinobu
  full_name: Fudamoto, Yoshinobu
  last_name: Fudamoto
- first_name: Seiji
  full_name: Fujimoto, Seiji
  last_name: Fujimoto
- first_name: Lukas J
  full_name: Furtak, Lukas J
  last_name: Furtak
- first_name: Karl
  full_name: Glazebrook, Karl
  last_name: Glazebrook
- first_name: Rashmi
  full_name: Gottumukkala, Rashmi
  last_name: Gottumukkala
- first_name: Kasper E
  full_name: Heintz, Kasper E
  last_name: Heintz
- first_name: Vasily
  full_name: Kokorev, Vasily
  last_name: Kokorev
- first_name: Ivo
  full_name: Labbe, Ivo
  last_name: Labbe
- first_name: Michael V
  full_name: Maseda, Michael V
  last_name: Maseda
- first_name: Ian
  full_name: McConachie, Ian
  last_name: McConachie
- first_name: Themiya
  full_name: Nanayakkara, Themiya
  last_name: Nanayakkara
- first_name: Erica
  full_name: Nelson, Erica
  last_name: Nelson
- first_name: Przemysław
  full_name: Nowaczyk, Przemysław
  last_name: Nowaczyk
- first_name: Pascal A
  full_name: Oesch, Pascal A
  last_name: Oesch
- first_name: Hans-Walter
  full_name: Rix, Hans-Walter
  last_name: Rix
- first_name: David J
  full_name: Setton, David J
  last_name: Setton
- 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: Fabian
  full_name: Walter, Fabian
  last_name: Walter
- first_name: Bingjie
  full_name: Wang, Bingjie
  last_name: Wang
- first_name: Andrea
  full_name: Weibel, Andrea
  last_name: Weibel
- first_name: Arjen
  full_name: van der Wel, Arjen
  last_name: van der Wel
citation:
  ama: 'de Graaff A, Hviding RE, Naidu RP, et al. Little red dots host black hole
    stars: A unified family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy.
    <i>Monthly Notices of the Royal Astronomical Society</i>. 2026;551(3). doi:<a
    href="https://doi.org/10.1093/mnras/stag1567">10.1093/mnras/stag1567</a>'
  apa: 'de Graaff, A., Hviding, R. E., Naidu, R. P., Greene, J. E., Miller, T. B.,
    Leja, J., … van der Wel, A. (2026). Little red dots host black hole stars: A unified
    family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy. <i>Monthly Notices
    of the Royal Astronomical Society</i>. Oxford University Press. <a href="https://doi.org/10.1093/mnras/stag1567">https://doi.org/10.1093/mnras/stag1567</a>'
  chicago: 'de Graaff, Anna, Raphael E Hviding, Rohan P Naidu, Jenny E Greene, Tim
    B Miller, Joel Leja, Jorryt J Matthee, et al. “Little Red Dots Host Black Hole
    Stars: A Unified Family of Gas-Reddened AGN Revealed by JWST/NIRSpec Spectroscopy.”
    <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press,
    2026. <a href="https://doi.org/10.1093/mnras/stag1567">https://doi.org/10.1093/mnras/stag1567</a>.'
  ieee: 'A. de Graaff <i>et al.</i>, “Little red dots host black hole stars: A unified
    family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy,” <i>Monthly
    Notices of the Royal Astronomical Society</i>, vol. 551, no. 3. Oxford University
    Press, 2026.'
  ista: 'de Graaff A, Hviding RE, Naidu RP, Greene JE, Miller TB, Leja J, Matthee
    JJ, Brammer G, Katz H, Bezanson R, Boogaard LA, Bose S, Chisholm J, Cleri NJ,
    Dayal P, Feldmann R, Fudamoto Y, Fujimoto S, Furtak LJ, Glazebrook K, Gottumukkala
    R, Heintz KE, Kokorev V, Labbe I, Maseda MV, McConachie I, Nanayakkara T, Nelson
    E, Nowaczyk P, Oesch PA, Rix H-W, Setton DJ, Torralba Torregrosa A, Walter F,
    Wang B, Weibel A, van der Wel A. 2026. Little red dots host black hole stars:
    A unified family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy. Monthly
    Notices of the Royal Astronomical Society. 551(3), stag1567.'
  mla: 'de Graaff, Anna, et al. “Little Red Dots Host Black Hole Stars: A Unified
    Family of Gas-Reddened AGN Revealed by JWST/NIRSpec Spectroscopy.” <i>Monthly
    Notices of the Royal Astronomical Society</i>, vol. 551, no. 3, stag1567, Oxford
    University Press, 2026, doi:<a href="https://doi.org/10.1093/mnras/stag1567">10.1093/mnras/stag1567</a>.'
  short: A. de Graaff, R.E. Hviding, R.P. Naidu, J.E. Greene, T.B. Miller, J. Leja,
    J.J. Matthee, G. Brammer, H. Katz, R. Bezanson, L.A. Boogaard, S. Bose, J. Chisholm,
    N.J. Cleri, P. Dayal, R. Feldmann, Y. Fudamoto, S. Fujimoto, L.J. Furtak, K. Glazebrook,
    R. Gottumukkala, K.E. Heintz, V. Kokorev, I. Labbe, M.V. Maseda, I. McConachie,
    T. Nanayakkara, E. Nelson, P. Nowaczyk, P.A. Oesch, H.-W. Rix, D.J. Setton, A.
    Torralba Torregrosa, F. Walter, B. Wang, A. Weibel, A. van der Wel, Monthly Notices
    of the Royal Astronomical Society 551 (2026).
das_tickbox: '1'
dataavailabilitystatement: "All data used in this work are publicly available through
  the\r\nDAWN JWST Archive (https://dawn-cph.github.io/dja/index.h\r\ntml). The spectra
  used in this work are part of version 4.5 of the\r\nDJA (G. Brammer & F. Valentino
  2025). We also release our complete LRD catalogue, together with all key measurements
  made All data used in this work are publicly available through the\r\nDAWN JWST
  Archive (https://dawn-cph.github.io/dja/index.h\r\ntml). The spectra used in this
  work are part of version 4.5 of the\r\nDJA (G. Brammer & F. Valentino 2025). We
  also release our complete LRD catalogue, together with all key measurements made
  in the modified blackbody fitting and emission-line fitting. The\r\ntable can be
  found at https://doi.org/10.5281/zenodo.21977747,\r\nand its contents are described
  in Appendix B.\r\n\r\n"
date_created: 2026-09-17T11:06:40Z
date_published: 2026-09-01T00:00:00Z
date_updated: 2026-10-01T11:31:16Z
day: '01'
ddc:
- '520'
department:
- _id: JoMa
doi: 10.1093/mnras/stag1567
external_id:
  arxiv:
  - '2511.21820'
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fulldoi: https://doi.org/10.1093/mnras/stag1567
has_accepted_license: '1'
intvolume: '       551'
issue: '3'
language:
- iso: eng
month: '09'
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: yes
scopus_import: '1'
status: public
supplementarymaterial: yes
title: 'Little red dots host black hole stars: A unified family of gas-reddened AGN
  revealed by JWST/NIRSpec 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: 551
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...