EVOLUTIONARY STATUS OF RV TRIANGULI AND ITS RELATED ALGOL-TYPE BINARIES

Abstract

We present CCD photometry for the Algol-type binary RV Trianguli observed during three nights in 2007 November. The photometric solution was derived from our VR observations by using the Wilson–Devinny program. The results indicated that RV Tri is a semidetached binary with a mass ratio of q = 0.306 (± 0.005). Based on 236 light minimum times, the orbital period change of RV Tri was analyzed in detail. We discovered that a secular decrease exists with two cyclic variations. The long-term period decreases at a rate of dP/dt =− 6.07 × 10 −8 days yr −1 , which may be due to mass and angular momentum loss. Two cyclic variations (i.e., P3 = 25.34 yr and A3 = 0. d 0029, and P4 = 10.30 yr and A4 = 0. d 0026) may be attributed to the unseen third and fourth bodies, respectively, which can be weakly identified by the photometric solution. If the existence of the two additional bodies is true, this binary may be a quadruple star. From 22 Algol binary systems with orbital periods decreasing, the relations of P − dP/dt and P − f were determined. With the orbital period decrease, dP/dt also decreases, indicating that mass and angular momentum loss will become slower. However, the fill-out factor of the primary f will increase as the period decreases, which will finally result in the primary filling its Roche lobe. Therefore, this kind of binary will evolve into a contact configuration.