Abstract
Themajority of hot subdwarf stars are low-mass core-helium-burning stars. Their atmospheres are generally helium deficient; however, a minority have extremely helium-rich surfaces. An additional fraction have an intermediate surface-helium abundance, occasionally accompanied by peculiar abundances of other elements. We have identified a sample of 88 hot subdwarfs including 38 helium-deficient, 27 intermediate-helium and 23 extreme-helium stars for which radial-velocity and proper-motion measurements, together with distances, allow a calculation of galactic space velocities. We have investigated the kinematics of these three groups to determine whether they belong to similar or different Galactic populations. The majority of helium-deficient subdwarfs in our sample show a kinematic distribution similar to that of thick disc stars. Helium-rich sdBs show a more diverse kinematic distribution. Although the majority are probably disc stars, a minority show a much higher velocity dispersion consistent with membership of a Galactic halo population. Several of the halo subdwarfs are members of the class of 'heavy-metal' subdwarfs discovered by Naslim et al.
Original language | English |
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Pages (from-to) | 68-82 |
Number of pages | 15 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 467 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2017 |
Externally published | Yes |
Keywords
- Chemically peculiar
- Kinematics and dynamics
- Stars
- Stars
- Subdwarfs
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science