The low mass ratio contact binary system V728 Herculis

We present the orbital period study and the photometric analysis of the contact binary system V728 Her. Our orbital period analysis shows that the period of the system increases (dP/dt = 1.92 x 10(-7)dyr(-1)) and the mass transfer rate from the less massive component to more massive one is 2.51 x 10(-8) M(circle dot)y(-1). In addition, an advanced sinusoidal variation in period can be attributed to the light-time effect by a tertiary component or the Applegate mechanism triggered by the secondary component. The simultaneous multicolor BVR light and radial velocity curves solution indicates that the physical parameters of the system are M-1 = 1.8M(circle dot), M-2 = 0.28M(circle dot), R-1 = 1.87R(circle dot), R-2 = 0.82R(circle dot), L-1 = 5.9L(circle dot), and L-2 = 1.2L(circle dot). We discuss the evolutionary status and conclude that V728 Her is a deep (f = 81%), low mass ratio (q = 0.16) contact binary system. (C) 2015 Elsevier B.V. All rights reserved.