Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II. Kinematics

0534444 - ASÚ 2021 RIV US eng J - Journal Article
Luo, Y. - Németh, Péter - Li, Q.
Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II. Kinematics.
Astrophysical Journal. Roč. 898, č. 1 (2020), č. článku 64. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA ČR(CZ) GA18-20083S
Institutional support: RVO:67985815
Keywords : blue hook stars * white-dwarfs * atmospheric parameters
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.877, year: 2020
Method of publishing: Limited access
https://doi.org/10.3847/1538-4357/ab98f3

We present a kinematic population classification of the four hot subdwarf helium groups based on their positions in the U - V velocity diagram, the J(Z)- eccentricity diagram, and their Galactic orbits. The overall tendency of the fractional distributions of the four hot subdwarf helium groups in the halo, thin disk, and thick disk is largely consistent with the findings reported by Luo et al. based on LAMOST DR5, which appears to support predictions of binary population synthesis. He-deficient stars with -2.2 <= log(y) < -1 likely originate from a stable Roche lobe overflow channel, He-deficient stars with log(y) < -2.2 from the common envelope ejection channel, and He-rich stars with log(y) >= 0 from the merger channel of double He white dwarf stars. The fraction of He-rich hot subdwarf stars with -1 <= log (y) < 0 in the thin disk and the halo is far higher than that in the thick disk, which implies that these stars have different formation channels in the thin disk and in the halo.
Permanent Link: http://hdl.handle.net/11104/0312637