@article{600357570a714990bddcd46603c1bf16,
title = "Kinematics of subluminous O and B stars by surface helium abundance",
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.",
keywords = "Chemically peculiar, Kinematics and dynamics, Stars, Stars, Subdwarfs",
author = "P. Martin and Jeffery, {C. S.} and N. Naslim and Woolf, {V. M.}",
note = "Funding Information: This research has made use of the SIMBAD data base, operated at CDS, Strasbourg, France, and is also based on data obtained from the ESO Science Archive Facility. We are grateful to James Murphy, then of St Malachy's College, Belfast, who during 2012 July first made the measurements shown Table 1 whilst holding a Nuffield Science Bursary at the Armagh Observatory. The Armagh Observatory is funded by direct grant from the Northern Ireland Dept. for Communities. This work has made use of data from the European Space Agency (ESA) mission Gaia,1 processed by the Gaia Data Processing and Analysis Consortium (DPAC).2 Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Funding Information: We are grateful to James Murphy, then of St Malachy{\textquoteright}s College, Belfast, who during 2012 July first made the measurements shown Table 1 whilst holding a Nuffield Science Bursary at the Armagh Observatory. The Armagh Observatory is funded by direct grant from the Northern Ireland Dept. for Communities. Funding Information: This work has made use of data from the European Space Agency (ESA) mission Gaia,1 processed by the Gaia Data Processing and Analysis Consortium (DPAC).2 Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Publisher Copyright: {\textcopyright} 2016 The Authors.",
year = "2017",
doi = "10.1093/mnras/stw3305",
language = "English",
volume = "467",
pages = "68--82",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}