Single and Composite Hot Subdwarf Stars in the Light of 2MASS Photometry: Extreme Horizontal Branch Stars and Related Objects (Guest Editor: P.F.L. Maxted)

Author： Stark M.A. Wade Richard A. Berriman G.B.

Publisher： Springer Publishing Company

ISSN： 0004-640X

Source： Astrophysics and Space Science, Vol.291, Iss.3, 2004-01, pp. : 333-336

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Utilizing the Two Micron All Sky Survey (2MASS) All-Sky Data Release Catalog, we have retrieved useful near-IR J, H and K_S magnitudes for more than 800 hot subdwarfs (sdO and sdB stars) drawn from the Catalogue of Spectroscopically Identified Hot Subdwarfs (Kilkenny, Heber, and Drilling, 1988, 1992). This sample size greatly exceeds previous studies of hot subdwarfs.We find that of the hot subdwarfs in Kilkenny et al., ∼40% in a magnitude-limited sample have colors that are consistent with the presence of an unresolved late-type (FGK) companion. Binary stars are over-represented in a magnitude-limited sample. In an approximately volume-limited sample the fraction of composite-color binaries is ∼25%.