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We present new observations for the eclipsing binary EP Aurigae, which were performed by using three small telescopes in China from 2003 December to 2014 January. With the updated 2003 version of the Wilson–Devinney code, the photometric elements were deduced from three sets of light curves. Based on all available eclipsing times, the orbital period changes were investigated. It is discovered that the ( O – C ) curve may show an existence of light-time effect due to an unseen third body, which was weakly identified by the photometric solution. The modulated period and amplitude of the cyclic variation are P 3 = 71.2 ( ± 8.0 ) yr and A = 0.0101 ( ± 0.0008 ) day , respectively. In the co-planar orbit with the binary system, the mass of the third body is M 3 = 0.18 ( ± 0.02 ) M ⊙ . The photometric results imply that EP Aur is an Algol-type binary with a mass ratio of q = 0.831 ( ± 0.004 ) . Its primary component almost fills its Roche lobe. Therefore, EP Aur may consist of a normal main-sequence star and a cool Roche-lobe filling subgiant, which may be undergoing rapid mass transfer. [ABSTRACT FROM AUTHOR]

Abstract: CCD photometric observations of the shortest period field contact binary, GSC 1387-0475, obtained in the observing season in 2008–2009, are presented. From new observations, eleven light minimum times were derived and the orbital period was revised. The light curves in BVR bands were analyzed using the W-D program. It is found that GSC 1387-0475 is an overcontact binary. The derived absolute physical parameters of this binary are: , , and . From the LogL-LogM diagram, the primary component is found to be an evolved star. The additional component of GSC 1387-0475 may remove angular momentum from the central system. With the angular momentum decreasing, the separation between components may decrease, which will cause the inner and out critical Roche lobes to shrink, resulting in an increase degree of overcontact. Finally, GSC 1387-0475 with a deep overcontact degree (i.e., ) may evolve into a rapid-rotating single star. [Copyright &y& Elsevier]