THE OVERCONTACT BINARY V563 LYRAE

Abstract

Radial velocity (RV) and light curve (LC) data for the overcontact binary V563 Lyr have been obtained and analysed with the 2003 version of the WilsonDevinney (WD) code with results K1 = 147.4 ± 2.1 km/s, K2 = 247.2 ± 1.1 km/s, RVγ = 22.5 ± 1.5 km/s, qsp = 0.596 ± 0.008, M1 = 2.49(4)M☉, M2 = 1.45(4)M☉, R1 = 2.23(2)R☉, R2 = 1.81(2)R☉. A third component was identified, with radial velocity RV3 = 18.8 ± 6.7 km/s. Inserting the derived parameters of the eclipsing pair into a Log (L)-Log (Teff) plot for each star using data from Yakut and Eggleton (2005) suggested that both stars are over-luminous and evolved to, and perhaps past, the terminal age main sequence (TAMS). The companion (star 3) has a spectral type of A0 ± 1 spectral subclass but cannot be gravitationally bound to the eclipsing pair, as its flux would dominate that of the pair, which was not observed. The companion must lie at some other distance.