Details

Autor(en) / Beteiligte

• Dawson, H
• Geier, S
• Heber, U
• Pelisoli, I
• Dorsch, M
• Schaffenroth, V
• Reindl, N
• Culpan, R
• Pritzkuleit, M
• Vos, J
• Soemitro, A A
• Roth, M M
• Schneider, D
• Uzundag, M
• Vučković, M
• L. Antunes Amaral
• Istrate, A G
• Justham, S
• Østensen, R H
• Telting, J H
• Djupvik, A A
• Raddi, R
• Green, E M
• Jeffery, C S
• Kepler, S O
• Munday, J
• Steinmetz, T
• Kupfer, T

Titel

A 500 pc volume-limited sample of hot subluminous stars

Ist Teil von

• Astronomy and astrophysics (Berlin), 2024-06, Vol.686

Ort / Verlag

Heidelberg: EDP Sciences

Erscheinungsjahr

2024

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 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 = 6.15−0.53+1.16 × 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.