Two contact binaries at different evolutionary stages in the globular cluster NGC 6397

	Two contact binaries at different evolutionary stages in the globular cluster NGC 6397
	Li K(李凯)1,2,3 ; Qian SB(钱声帮)1,2
刊名	NEW ASTRONOMY
	2013-12
卷号	25 页码:12-18
关键词	Globular clusters: Individual: NGC 6397 Stars: binaries: close Stars: binaries: eclipsing Stars: blue: stragglers
ISSN号	1384-1076
通讯作者	Li, K (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	NGC 6397 is the second closest globular cluster in the Milky Way. Photometric solutions of two EW-type binaries, V7 and V8, in this cluster are presented by analyzing two sets light curves obtained by Kaluzny et al. We find that both of the two systems are contact binaries. V7 is a shallow contact W-type W UMa system with a contact degree of f=2.7%, while V8 is an extremely low mass ratio (similar to 0.159) A-type W UMa system with a contact degree of f=46.1%. We also analyzed the orbital period changes of the two binaries, long-term period increase has been detected for both binaries. The period increase may be caused by mass transfer from the less massive component to the more massive one. As the period increase, for V7, it will evolve to the expanding stage of the thermal relaxation oscillation cycle; for V8, it will merge into a rapidly rotating single star after the orbital angular momentum is less than three times the total spin angular momentum. On the color-magnitude diagram of NGC 6397, V7 occupies a position close to the cluster turn off,'while V8 is located in faint blue straggler region. Therefore, V8 is an eclipsing blue straggler candidate and could be formed by mass transfer. By comparing the two binaries with contact binaries in the field, we find that evolutionary processes of contact binaries in the globular cluster low metallicity environment may be similar with that of contact binaries in the field high metallicity environment. (C) 2013 Elsevier B.V. All rights reserved.
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]	URSAE MAJORIS SYSTEMS ; PHYSICAL PARAMETERS ; MARGINAL-CONTACT ; ECLIPSING BINARIES ; MAIN-SEQUENCE ; COMAE BERENICES ; LIGHT CURVES ; STARS ; COMPONENTS ; NGC-6397
收录类别	SCI
原文出处	http://www.sciencedirect.com/science/article/pii/S1384107613000389
语种	英语
WOS记录号	WOS:000322805300003
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5874]
专题	云南天文台_双星与变星研究组云南天文台_中国科学院天体结构与演化重点实验室
作者单位	1.National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P. O. Box 110, 650011 Kunming, China 2.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, China 3.University of the Chinese Academy of Sciences, Beijing 100049, China
推荐引用方式 GB/T 7714	Li K,Qian SB. Two contact binaries at different evolutionary stages in the globular cluster NGC 6397[J]. NEW ASTRONOMY,2013,25:12-18.
APA	Li K,&Qian SB.(2013).Two contact binaries at different evolutionary stages in the globular cluster NGC 6397.NEW ASTRONOMY,25,12-18.
MLA	Li K,et al."Two contact binaries at different evolutionary stages in the globular cluster NGC 6397".NEW ASTRONOMY 25(2013):12-18.