A photometric study of a total-eclipse contact binary V458 Mon

We present light curve solution of V458 Mon firstly by using the Wilson-Devinney code. The total eclipse and deep minima of the light curves of V458 Mon enable us to determine reliable orbital parameters of the binary system. The solution suggests that V458 Mon is a low mass ratio binary system with about 0.2 possessing a moderate degree of contact. The long-term period investigation showed that the period of V458 Mon is increasing at $dP/dt=+2.59\times 10^{-7}days/yr$, which could be the reason of mass transfer from the less massive component to more massive primary one, together with a periodic change. The oscillation in orbital period may be due to an unseen tertiary companion with the mass about $M_3=1.8M_{\odot }$ . After removing these change, there is still a weak cyclic change maybe due to magnetic activity. With the increase in orbital period of binary, the separation increases and mass ratio decreases which eventually leads V458 Mon towards merger.