On the lower limit of contact binary star periods

Abstract

ABSTRACT Data for 405 contact binary systems extracted from a recent compilation are supplemented by information from the literature for an additional ten ultrashort period (P < 0.2 d) binaries. This is used to calibrate period–luminosity–temperature relations for contact binaries. The derived relations are applied to a standard mean temperature–luminosity tabulation to obtain predicted periods for contact systems over the spectral range M9.5–A2. Minimum periods in the range 0.08–0.15 d follow, depending on the precise period–luminosity–temperature model fitted.