On the Period Variation of the W UMa-type Contact Binary V502 Ophiuchi

The variation in the orbital period of the W UMa type contact binary V502 Oph is analyzed. The orbital period exhibits a wavelike variation with a periodicity of 23.0 years and an amplitude of Delta P = 1.24 x 10(-6) days superimposed on secular decrease of dP/dt = 1.68 x 10(-7) day per year. The long-term decrease may be accompanied by the contraction of the secondary at a rate of 83 m per year and a mass transfer rate from the primary to the secondary of 4.28 x 10(-8) M-. per year. The short-term oscillation may be explained by the presence of a third component. Orbital elements of the third body and its possible mass are presented.