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A 500 pc volume-limited sample of hot subluminous stars: I. Space density, scale height, and population properties

We present the first volume-limited sample of spectroscopically confirmed hot subluminous stars out to 500 pc, defined using the accurate parallax measurements from the Gaia space mission data release 3 (DR3). The sample comprises a total of 397 members, with 305 (∼77%) identified as hot subdwarf st...

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Main Authors: Dawson, Harry (Author) , Geier, S. (Author) , Heber, U. (Author) , Pelisoli, I. (Author) , Dorsch, M. (Author) , Schaffenroth, V. (Author) , Reindl, Nicole (Author) , Culpan, R. (Author) , Pritzkuleit, M. (Author) , Vos, J. (Author) , Soemitro, A. A. (Author) , Roth, M. M. (Author) , Schneider, D. (Author) , Uzundag, M. (Author) , Vučković, M. (Author) , Amaral, L. Antunes (Author) , Istrate, A. G. (Author) , Justham, S. (Author) , Østensen, R. H. (Author) , Telting, J. H. (Author) , Djupvik, A. A. (Author) , Raddi, R. (Author) , Green, E. M. (Author) , Jeffery, C. S. (Author) , Kepler, S. O. (Author) , Munday, J. (Author) , Steinmetz, T. (Author) , Kupfer, T. (Author)
Format: Article (Journal)
Language:English
Published: June 2024
In: Astronomy and astrophysics
Year: 2024, Volume: 686, Pages: 1-21
ISSN:1432-0746
DOI:10.1051/0004-6361/202348319
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202348319
Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2024/06/aa48319-23/aa48319-23.html
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Author Notes:H. Dawson, S. Geier, U. Heber, I. Pelisoli, M. Dorsch, V. Schaffenroth, N. Reindl, R. Culpan, M. Pritzkuleit, J. Vos, A.A. Soemitro, M.M. Roth, D. Schneider, M. Uzundag, M. Vučković, L. Antunes Amaral, A.G. Istrate, S. Justham, R.H. Østensen, J.H. Telting, A.A. Djupvik, R. Raddi, E.M. Green, C.S. Jeffery, S.O. Kepler, J. Munday, T. Steinmetz, and T. Kupfer
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Summary:We present the first volume-limited sample of spectroscopically confirmed hot subluminous stars out to 500 pc, defined using the accurate parallax measurements from the Gaia space mission data release 3 (DR3). The sample comprises a total of 397 members, with 305 (∼77%) identified as hot subdwarf stars, including 83 newly discovered systems. Of these, we observe that 178 (∼58%) are hydrogen-rich sdBs, 65 are sdOBs (∼21%), 32 are sdOs (∼11%), and 30 are He-sdO/Bs (∼10%). Among them, 48 (∼16%) exhibit an infrared excess in their spectral energy distribution fits, suggesting a composite binary system. The hot subdwarf population is estimated to be 90% complete, assuming that most missing systems are these composite binaries located within the main sequence (MS) in the Gaia colour-magnitude diagram. The remaining sources in the sample include cataclysmic variables, blue horizontal branch stars, hot white dwarfs, and MS stars. We derived the mid-plane density ρ0 and scale height hz for the non-composite hot subdwarf star population using a hyperbolic sechant profile (sech2). The best-fit values are ρ0 = 5.17 ± 0.33 × 10−7 stars pc−3 and hz = 281 ± 62 pc. When accounting for the composite-colour hot subdwarfs and their estimated completeness, the mid-plane density increases to ρ0 = 6.15+1.16 −0.53 × 10−7 stars pc−3. This corrected space density is an order of magnitude lower than predicted by population synthesis studies, supporting previous observational estimates.
Item Description:Veröffentlicht: 27 May 2024
Gesehen am 27.01.2025
Physical Description:Online Resource
ISSN:1432-0746
DOI:10.1051/0004-6361/202348319

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