GR Virginis: A deep overcontact binary

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	GR Virginis: A deep overcontact binary
	Qian, SB ; Yang, YG
刊名	ASTRONOMICAL JOURNAL
	2004-11-01
卷号	128 期号:5 页码:2430-2434
关键词	binaries : close binaries : eclipsing stars : evolution stars : individual (GR Virginis)
ISSN号	0004-6256
英文摘要	Orbital period variations of the low-mass ratio (q = 0.122) overcontact binary system, GR Vir, were investigated by using two new CCD times of minimum light and other photoelectric data compiled from literatures. It is found that the O-C residuals of GR Vir show a cyclic variation with a period of 19.3 yr and an amplitude of 0.0140 days while they are undergoing a long-term decrease (dP/dt = 4.32 x 10(-7) days yr(-1)). Meanwhile, the 1988 photoelectric observations from Cereda et al. were analyzed using the Wilson-Devinney method. Like some low-mass ratio overcontact binary stars (e.g., AW UMa), GR Vir is an A-type overcontact binary with a high degree of overcontact (f = 78.6%). By combining the spectroscopic solutions with the photometric elements, the absolute parameters of the system are determined as follows: M-1 = 1.36 M-circle dot, M-2 = 0.17 M-circle dot, a = 2.40 R-circle dot, R-1 = 1.42 R-circle dot, R-2 = 0.61 R-circle dot, L-1 = 2.87 L-circle dot, and L-2 = 0.48 L-circle dot. The long-term period decrease is interpreted as the result of mass transfer from the more massive component to the less massive one in combination with the angular momentum loss due to mass outflow from the L-2 point. The conditions in GR Vir resemble those in AW UMa. Both systems show a high degree of overcontact, low mass ratios, and secular shrinking of their orbits. As their orbital periods decrease, the shrinking of the inner and outer critical Roche lobes will cause the common convective envelope to become deeper, until finally the formation of single, rapid-rotation stars is inevitable. The period oscillation may by caused either by the presence of an unseen tertiary component (e.g., a white dwarf) or by magnetic activity on the part of the primary component.
WOS关键词	ORBITAL PERIOD MODULATION ; URSAE-MAJORIS ; CLOSE BINARIES ; MASS-RATIO ; AM LEONIS ; STARS ; PHOTOMETRY ; SYSTEM ; BV
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	UNIV CHICAGO PRESS
WOS记录号	WOS:000224866500034
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/37451]
专题	中国科学院国家天文台
通讯作者	Qian, SB
作者单位	1.Chinese Acad Sci, Natl Astron Observ, Yunnan Observ, Kunming 650011, Peoples R China 2.Chinese Acad Sci, United Lab Opt Astron, Beijing 100012, Peoples R China
推荐引用方式 GB/T 7714	Qian, SB,Yang, YG. GR Virginis: A deep overcontact binary[J]. ASTRONOMICAL JOURNAL,2004,128(5):2430-2434.
APA	Qian, SB,&Yang, YG.(2004).GR Virginis: A deep overcontact binary.ASTRONOMICAL JOURNAL,128(5),2430-2434.
MLA	Qian, SB,et al."GR Virginis: A deep overcontact binary".ASTRONOMICAL JOURNAL 128.5(2004):2430-2434.