A FAINT ECLIPSING BINARY ASSOCIATED WITH THE GALACTIC THICK DISK OR HALO

• Published in: Publications of the Astronomical Society of the Pacific 1988-06, Vol.100 (628), p.730-735
• Main Authors: DAVIDGE, T. J., PRITCHET, C. J.
• Format: Article
• Language: English
• Subjects: Astronomical magnitude; Astronomical objects; Astronomy; Binary and multiple stars; Calibration; Earth, ocean, space; Eclipsing binaries; Eclipsing binary stars; Exact sciences and technology; Galactic planes; Light curves; Mass ratio; Mass transfer; Milky Way galactic halo; Stars; Variable stars
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1086/132227

We present observations of a faint, red, short-period Galactic eclipsing binary discovered during a recent study of RR Lyrae variables in the halo of M 31. A possible light-curve solution, found using the Wilson-Devinney program, indicates that the components are of similar size and have temperatures of approximately 3700 and 2800 K. The solution also suggests that the components are not main-sequence objects and may have undergone mass transfer. A lower limit for the distance to the system is determined by assuming that mass transfer has occurred. The resulting displacement above the Galactic plane is sufficient to preclude the binary being a member of the thin disk. We also investigate the observed frequency of faint short-period eclipsing binaries at intermediate to high Galactic latitudes using data from published variable-star surveys. The surface density of observed eclipsing binaries, scaled with respect to that of all stars expected in the same field and magnitude interval as the detected variables, appears to be relatively constant over a large range of Galactic latitudes. It is also suggested that some of the eclipsing binaries discovered in past surveys could be members of the thick disk or halo.