Mass Transfer and Light Time Effect Studies for Au Serpentis

Abstract

Abstract:The orbital period changes of the W UMa eclipsing binary AU Ser are studied using the (O−C) method. We conclude that the period variation is due to mass transfer from the primary star to the secondary one at a very low and decreasing rate dP/dt = −8.872 × 10 −8 , superimposed on the sinusoidal variation due to a third body orbiting the binary with period 42.87 ± 3.16 years, orbital eccentricity e = 0.52 ± 0.12 and a longitude of periastron passage ω = 133• .7 ± 15. On studying the magnetic activity, we have concluded that the Applegate mechanism failed to describe the cycling variation of the (O − C) diagram of AU Ser.