Photometric Investigation of the Contact Binary GU Ori with High Metallicity

GU Ori was observed with the 1m telescope at Yunnan Observatories in 2005. To determine its physical properties, the Wilson-Devinney program is used. The results reveal that GU Ori is a W-subtype shallow contact binary with a more massive but cooler star 2. The mass of its two component stars are estimated to be M_1 = 0.45M_⊙, M_2 = 1.05M_⊙. The O'Connell effect was reported to be negative on the light curves observed in 2005. However, it changed to a positive one on the light curves observed from 2011 to 2012. The mean surface temperatures of star 2 (T_2) determined by the two sets of light curves were different, which may result from stellar activities. The O - C diagram shows that the period of GU Ori is decreasing at a rate of dP/dt=-6.24×10^-8day· year^-1, which may be caused by mass transfer from star 2 to star 1 with a rate of dM_2/dt= - 2.98×10^-8M_⊙/year. GU Ori is a contact binary with quite high metallicity.