中国科学院云南天文台机构知识库

We present multi-color photometric observations for two neglected near-contact binaries, IZ Mon (P = 0(d).177980) and AR Dra (P = c(d). 67584). By the aid of the updated W -D analysis code, the photometric solutions were deduced from the multi -color light curves (LCs). IZ Mon is a semi-detached binary with a mass ratio of q = 0.388(0.002), while AR Dra is a detached star with a mass ratio of q = 0.652( 0.002). The asymmetric LCs of IZ Mon were modeled by a hot spot on the secondary's surface, which may be attributed to mass transfer from the primary. Based on all collected eclipse times for two systems, we constructed their timing residual curves. The orbital period for IZ Mon may be continuously decreasing at a rate of dP/dt = 2.06(0.04) days yr 1, which may result from mass and angular momentum loss from the central system. For AR Dra, there exists a cyclic variation with a period of P-3 = 104.9(+/- 2.9) yr due to light-time orbit effect via the presence of the third body, whose mass is more than 0 28 (+/- 0.02) M-circle dot. Finally, two near-contact binaries, IZ Mon and AR Dra, will evolve into contact binaries.