Short-period near-contact binary systems at the beginning of the overcontact phase

	Short-period near-contact binary systems at the beginning of the overcontact phase
	Qian SB(钱声帮)1,2
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2002-11-11
卷号	336 期号:4 页码:1247-1255
关键词	binaries : close stars : evolution stars : mass-loss
ISSN号	0035-8711
通讯作者	Qian, SB (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	A detailed analysis of orbital period changes of seven near-contact binary stars (NCBs) (BL And, V473 Cas, XZ CMi, BV Eri, RU Eri, UU Lyn and GR Tau) with period less than 1 d has been performed and their respective O-C diagrams are formed and discussed. It is found that all systems analysed show secular period decreasing. For V473 Cas, the analysis of the period change was performed based on data collected by Moschner, Frank & Bastian. For XZ CMi, its period shows some complex changes, a possible cyclic oscillation is discovered to superpose on the secular decrease that can be explained either by the presence of a third body or by magnetic activity cycles of the components. Since the third-body assumption is consistent with the photometric solution of Rafert, XZ CMi may be a truly triple system. For BV Eri, the period decrease is only supported by weak evidence. All the seven systems are short-period NCBs with AF-type primary components where both components are filling or nearly filling the critical Roche lobe. As the period decreases, the separation between both components will be reducing and thus these systems will evolve into A-type overcontact binaries. The period decrease may be caused by mass transfer or/and by angular momentum loss via magnetic braking. Combined with the published data on the other systems of the same type, a possible statistical connection between orbital period P and its rate of decrease dP/dt is obtained: dP/dt = -5.3 x 10(-7) x P + 1.3 x 10(-7) d yr(-1). This correlation indicates that the smaller the orbital period P is, the smaller its rate of change dP/dt will be. The correlation found in this paper indicates that there may be a smooth transition from A- and F-type NCBs with period decreases to the A- and F-type overcontact binaries that have period increases, and in that sense one may postulate that the NCBs may be the progenitors of the A-type W UMa systems and will be oscillating around a marginal-contact state as predicted by thermal relaxation oscillation (TRO) theory.
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 ; XZ CANIS-MINORIS ; UBV PHOTOMETRY ; BV ERIDANI ; GR TAURI ; EVOLUTION ; LIGHT ; MASS
收录类别	SCI
原文出处	http://mnras.oxfordjournals.org/content/336/4/1247
语种	英语
WOS记录号	WOS:000178981200024
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5753]
专题	云南天文台_双星与变星研究组
作者单位	1.Yunnan Observatory, National Astronomical Observatories, Chinese Academy of Sciences, POBox 110, 650011 Kunming, China 2.United Laboratory of Optical Astronomy, Chinese Academy of Sciences (ULOAC), 100012 Beijing, China
推荐引用方式 GB/T 7714	Qian SB. Short-period near-contact binary systems at the beginning of the overcontact phase[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2002,336(4):1247-1255.
APA	Qian SB.(2002).Short-period near-contact binary systems at the beginning of the overcontact phase.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,336(4),1247-1255.
MLA	Qian SB."Short-period near-contact binary systems at the beginning of the overcontact phase".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 336.4(2002):1247-1255.