Two W-subtype contact binaries: GQ Boo and V1367 Tau

Abstract

Two contact binaries, GQ Boo and V1367 Tau, were observed and analysed with a new method to obtain the absolute parameters. The light-curve analysis shows that both of them are obvious W-subtype contact binaries, with much more massive but apparently cooler components (M-2/M-1 similar or equal to 2 and 4, T-2/T-1 similar or equal to 0.95 and 0.94). The orbital periods were studied using the O-C diagrams, and it is thought that the minima timings were heavily affected by the long-standing magnetic activities on the star surface, so the minima timings cannot represent the real period changes. The mass-radius relationships were proposed by the light-curve analysis alone, which is equivalent to the mean density. The density and temperature can determine the other absolute parameters in most of the time. With the almost complete star parameter space provided by PARSEC, approximate masses and radii were obtained (0.52 +/- 0.08M(circle dot) and 1.01 +/- 0.15M(circle dot) for GQ Boo, and 0.22 +/- 0.01M(circle dot) and 0.92 +/- 0.06M(circle dot) for V1367 Tau). The mass-radius relationship is a neglected useful tool to calculate the mass and radius, especially for the detached binaries.