A period study of V502 Ophiuchus

Abstract

All available published times of minima of a W-type contact binary V502 Oph have been compiled and critically examined. Ten times of minima were revisted from original observations, and five new times of minima derived from our own observations. A period study covering 53 yr of observations including 84 timings of minima light (63 of them from photoelectric observations) reveals that the orbital period of the system oscillates with a period of about 35 ± 2 yr and amplitude of about 0.020 ± 0.005 day while it undergoes a constant period decrease of about dP/dt ∼ −1.45 10 −7 d/yr