THE MULTI-COLOR LIGHT CURVES OF THE W UMa TYPE CONTACT BINARY EP ANDROMEDAE

被引:20
作者
Liao, W. -P. [1 ,2 ]
Qian, S. -B. [1 ,2 ,3 ]
Li, K. [1 ,2 ,3 ]
He, J. -J. [1 ,2 ]
Zhao, E. -G. [1 ,2 ]
Zhou, X. [1 ,2 ,3 ]
机构
[1] Chinese Acad Sci, Yunnan Observ, Kunming 650011, Peoples R China
[2] Chinese Acad Sci, Key Lab Struct & Evolut Celestial Objects, Kunming 650011, Peoples R China
[3] Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China
基金
中国科学院西部之光基金;
关键词
binaries: close; binaries: eclipsing; stars: individual (EP Andromedae); CYCLIC PERIOD CHANGES; CLOSE BINARIES; ADDITIONAL COMPONENTS; EVOLUTIONARY STATUS; ECLIPSING BINARY; SYSTEMS; CYGNI; DEEP; DRACONIS; COMPANION;
D O I
10.1088/0004-6256/146/4/79
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
New multi-color CCD photometric light curves of the eclipsing binary EP And were obtained over six nights in 2006, 2011, and 2012. Using the Wilson-Devinney code, we computed the photometric elements of this system. It was discovered that EP And is a W-type W UMa contact binary system with a mass ratio of q = 2.685 and a degree of contact factor f = 24.9%, rather than an A-type system. Combining 28 newly determined times of minimum light derived from 1999 to 2012 with others collected from the literature, a long-term increase (dP/dt = +5.22 x 10(-8) days yr(-1)) with a sinusoidal variation (A = 0.0109 days; T = 40.89 yr) in the orbital period was found. The orbital period secular increases may be interpreted as conservative mass transfer from the less massive component to the more massive one, and cyclic variations of the orbital period may be caused by the light-travel time effect through the presence of a third body. The evolutionary status and the age of the system are also discussed.
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页数:7
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