Kinematics of subluminous O and B stars by surface helium abundance

P. Martin, C. S. Jeffery, N. Naslim, V. M. Woolf

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


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 languageEnglish
Pages (from-to)68-82
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 2017
Externally publishedYes


  • Chemically peculiar
  • Kinematics and dynamics
  • Stars
  • Stars
  • Subdwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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