WZ CEPHEI: A CLOSE BINARY AT THE BEGINNING OF CONTACT PHASE

	WZ CEPHEI: A CLOSE BINARY AT THE BEGINNING OF CONTACT PHASE
	Zhu LY(朱俐颖)1,2 ; Qian SB(钱声帮)1,2
刊名	ASTRONOMICAL JOURNAL
	2009-12
卷号	138 期号:6 页码:2002-2006
关键词	binaries: close binaries: eclipsing stars: evolution stars: individual (WZ Cephei)
ISSN号	0004-6256
通讯作者	Zhu, LY (reprint author), Chinese Acad Sci, Natl Astron Observ, Yunnan Observ, POB 110, Kunming 650011, Peoples R China.
产权排序	第一完成单位
英文摘要	Photometric photoelectric data of the short-period close binary system, WZ Cephei, are presented. A new photometric analysis with the 2003 version of the Wilson-Devinney method confirmed that it is a shallow contact binary (f similar to 13.3%) with a high level of spot activity on the primary component. Combining new determined times of light minimum with the others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 34.2 years and an amplitude of 0(d).013, was discovered to be superimposed on a long-term period decrease (dP/dt = -8.8 x 10(-8) days year(-1)). Both the secular period decrease and the shallow contact configuration suggest that this binary system is at the beginning of contact phase. It is on the way to evolving into a normal overcontact phase via secular angular momentum loss and/or mass transfer from the more massive component to the less massive one. The period oscillation can be explained either by the light-time effect due to the presence of a third body or by magnetic activity. On the one hand, if it is caused by the light-time effect, the mass and the orbital radius of the additional body should be m(3) = 0.17 M(circle dot) and a(3) = 26.6 AU, respectively, when this body is coplanar to the orbit of the eclipsing pair. On the other hand, since the system shows high levels of spot activity, the period oscillation may be explained as a consequence of magnetic cycles. In this case, the required variation of the quadrupole moment is calculated to be 9.2 x 10(49) g cm(2).
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	ORBITAL PERIOD MODULATION ; TERM STARSPOT EVOLUTION ; ACTIVITY CYCLE ; LIGHT CURVES ; PHOTOMETRIC MEASUREMENTS ; OVERCONTACT PHASE ; AR LACERTAE ; MASS ; CASSIOPEIAE ; PERSEI
收录类别	SCI
原文出处	http://iopscience.iop.org/1538-3881/138/6/2002/
语种	英语
WOS记录号	WOS:000271630200036
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5816]
专题	云南天文台_双星与变星研究组
作者单位	1.National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming, China 2.Laboratory for the Structure and Evolution of Celestial Bodies, Chinese Academy of Sciences P.O. Box 110, 650011 Kunming, China
推荐引用方式 GB/T 7714	Zhu LY,Qian SB. WZ CEPHEI: A CLOSE BINARY AT THE BEGINNING OF CONTACT PHASE[J]. ASTRONOMICAL JOURNAL,2009,138(6):2002-2006.
APA	Zhu LY,&Qian SB.(2009).WZ CEPHEI: A CLOSE BINARY AT THE BEGINNING OF CONTACT PHASE.ASTRONOMICAL JOURNAL,138(6),2002-2006.
MLA	Zhu LY,et al."WZ CEPHEI: A CLOSE BINARY AT THE BEGINNING OF CONTACT PHASE".ASTRONOMICAL JOURNAL 138.6(2009):2002-2006.