| 其他摘要 | The structures of G-type components in solar-like binaries are the same as the sun’s. But, because of the faster rotation and the deeper convection, they show much more stronger sunlike activities, i.e., dark-spots and flares. In the first section of the present paper, the definition, observational characters, research status of contact binary are introduced. Later, some methods about photometric study of binary are simply illustrated. In the second section, according to the observation and study on three G-type solar-like contact binaries, some results are following as: 1. Using the 60-cm telescope at Yunnan Astronomical Observatory, it is the first time to obtain the complete V RI bands light curves for GSC 0763-0572,which were carried out for three nights. Based on all available times of light minimum, we found that the orbital period is undergoing a continuous increase at rate of dP/dt = +5.81(33) × 10−7days year−1. We analyzed the V RI light curves by using the Wilson-Devinney code, it is confirmed that GSC 0763-0572 is A-subtype contact binary with the mass ration of q = 0.2330, the degree of contact factor of f =31.0%. Meanwhile, we estimated that M1 = 1.23M⊙, M2 =0.29M⊙. It is inferred that GSC 0763-0572 may presently be in an expanding state of thermal relaxation oscillation, finally evolve into a rapid-rotating single star. 2. CCD photometric light curves of W UMa-type binary system CW Cas in 2004 and 2011 are obtained with the 85-cm telescope at Xinglong Station of National Astronomical Observatory. It was found that the V band light curve shows O’Connell effect in 2004, while BV RI light curves in 2011 are nearly symmetric. Compared with light curves in different observing seasons, the variation indicates that there are dark-spot activities on the surface of the components. With spot models of the 2003 version of the Wilson-Devinney code, we get photometric solutions. Based on all available photoelectric and CCD light minimum, we analyzed the change of orbital period. The period of the system shows a cyclic period change (P3 = 45.95years, A3 = 0.0069days) superimposed on the continual decrease (dP/dt = −1.15 × 10−7days year−1). The long-term period decrease can be explained by mass transfer from the more massive one to the less one or an enhanced stellar wind and angular momentum loss(AML). The Applegate mechanism probably can not describe the cyclic period change, which change was explained as the light-travel time effect of the presence of a tertiary companion. 3. With the 1-m telescope at Yunnan Astronomical Observatory, we have analyzed V RI light curves of V524 Mon with the 2003 version of the Wilson Devinney code. We confirm that V524 Mon is a shallow W-type contact binary system with a mass ratio of q = 2.099 and a degree of contact factor of f = 7.7%. Based on the new eight times of light minimum and those published by previous investigators, we find that the orbital period of the binary shows a long-term decrease while it undergoes a cyclic oscillation. The long-term period decrease can be explained by mass transfer from the more massive one to the less one. The cyclic change explained as the light-travel time effect reveals the presence of a tertiary companion. The marginal contact configuration and the continuous period decrease, both suggest that it may be a newly formed contact binary. |
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