New Observations of V530 Andromedae: a Critical Contact Binary?

摘要

We follow up on single coverage UBVR_cI_c light curves taken in 2011 and analyses. Our present BVR_cI_c light curves with ample coverage were taken October and November 2013 and January 2014 with the Dark Sky Observatory 0.81-meter reflector of Appalachian State University. They reveal the early-type V530 And as a totally eclipsing shallow or critical contact solar-type binary rather than semidetached near-contact one. In our extended period study, over a 14.25-year interval, we find a continuously decreasing period. This fits the scenario of magnetic braking for solar-type binaries. The temperatures of the primary and secondary components are estimated at 6750 and 6030 K. The component temperature difference is large for a contact binary. The fill-out, however, is a mere 5% so it is near critical contact. The mass ratio, M_2/M_1, was found to be 0.386. Two star spots, probably magnetic in origin, were determined. We suspect that the binary has recently achieved physical contact for the first time.