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

Abstract

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 ∆P = 1.24 × 10 −6 days superimposed on secular decrease of dP/dt = 1.68 × 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 × 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.

Physical properties and evolutionary status of the W-subtype contact binary V502 Oph with a stellar companion

“…As for V502 Oph, lines of a third component were detected while spectroscopic observations were carried out (Hendry & Mochnacki 1998;Pribulla & Rucinski 2006). The light-travel time effect (LTTE) appearing on the observed-calculated (O −C) curve also confirmed the existence of a close-in tertiary component around the binary system (Yüce et al 2006;Liu & Yang 2006). Unfortunately, the former photometric solutions had not given any information about third light (l 3 ).…”

“…The light curves change over time and may indicate variable surface activity, which made it an ideal target to study the physical mechanism of O'Connell effect (Koju & Beaky 2015). The orbital period of V502 Oph was found to change continuously, according to the investigation by Kwee (1958); Kreiner (1971); Strauss (1976); Maddox & Bookmyer (1979); Hobart et al (1989); Derman & Demircan (1992); Yüce et al (2006) and Liu & Yang (2006).…”