摘要：New multi-band CCD light curves of three binaries W UMa-type V1175 Her, NSVS 2669503, and 1SWASPJ133417.80+394314.4are presented. Spectroscopic data for V1175 Her and NSVS 2669503 show that theirspectral types are G7V and K4V, respectively. Photometric solutions of these three objects were obtained with thehelp of the Wilson–Devinney program. We find that V1175 Her is a semi-detached binary star with a hot spotlocated on the secondary component, while NSVS 2669503 and 1SWASP J133417.80+394314.4are contacteclipsing binaries with contact factors of f=1.070±0.002% and f=21.250±0.005%, respectively. Moreover,we found that the orbital period of V1175 Her is increasing at a rate of (+3.1±0.1)×10 −7 daysyr −1 . Thisincrease may be attributed to a dM dt M 0.93 10 yr-1 mass-transfer rate from the primary to the secondary component. Finally, we discuss the evolutionary stage of the component stars of these three systems.
