Hot subdwarf stars from Gaia with LAMOST sp. II. RVs

These stars were identified by Lei+ (Paper I; 2020, J/ApJ/889/117) in Gaia DR2 with LAMOST DR6 and DR7 spectra. He-rich hot subdwarf stars with log(y)>=0 show the largest standard deviations of the Galactic velocity components and orbital parameters, while those with -1<=log(y)<=0 exhibit the second largest standard deviations.

The two groups of He-deficient stars with log(y){<}-1 show similar standard deviations, which are systematically lower compared to He-rich stars. We also 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+ (2019ApJ...881....7L) based on LAMOST DR5, which appears to support predictions of binary population synthesis.