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

Dawson H, Geier S, Heber U, Pelisoli I, Dorsch M, Schaffenroth V, Reindl N, Culpan R, Pritzkuleit M, Vos J, Soemitro AA, Roth MM, Schneider D, Uzundag M, Vučkoviä M, Antunes Amaral L, Istrate AG, Justham S, Astensen RH, Telting JH, Djupvik AA, Raddi R, Green EM, Jeffery CS, Kepler SO, Munday J, Steinmetz T, Kupfer T (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Astronomy & Astrophysics EDP Sciences

Book Volume: 686

Article Number: A25

DOI: 10.1051/0004-6361/202348319

Abstract

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 A-10a7 stars pca3 and hz = 281 ± 62 pc. When accounting for the composite-colour hot subdwarfs and their estimated completeness, the mid-plane density increases to ρ0 = 6.15a 0.53+1.16 A10a stars pca3. This corrected space density is an order of magnitude lower than predicted by population synthesis studies, supporting previous observational estimates.

Authors with CRIS profile

Ulrich Heber Professur für Astronomie und Astrophysik David Schneider Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut

Involved external institutions

Universität Potsdam DE Germany (DE) Nordic Optical Telescope ES Spain (ES) University of Valparaíso (UV) / Universidad de Valparaiso CL Chile (CL) Universitat Politècnica de Catalunya · BarcelonaTech (UPC) ES Spain (ES) University of Arizona US United States (USA) (US) Armagh Observatory GB United Kingdom (GB) Universidade Federal do Rio Grande do Sul (UFRGS) BR Brazil (BR) Isaac Newton Group of Telescopes (ING) ES Spain (ES) Universität Hamburg (UHH) DE Germany (DE) Radboud University Nijmegen NL Netherlands (NL) Max-Planck-Institut für Astrophysik / Max Planck Institute for Astrophysics DE Germany (DE) Recogito AT Austria (AT)

How to cite

APA:

Dawson, H., Geier, S., Heber, U., Pelisoli, I., Dorsch, M., Schaffenroth, V.,... Kupfer, T. (2024). A 500 pc volume-limited sample of hot subluminous stars: I. Space density, scale height, and population properties. Astronomy & Astrophysics, 686. https://doi.org/10.1051/0004-6361/202348319

MLA:

Dawson, H., et al. "A 500 pc volume-limited sample of hot subluminous stars: I. Space density, scale height, and population properties." Astronomy & Astrophysics 686 (2024).

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