The formation of EL CVn-type binaries

	The formation of EL CVn-type binaries
	Chen XF(陈雪飞)1,2,3 ; Maxted, P. F. L.4; Li J(李蛟)1,2,5 ; Han ZW(韩占文)1,2,3
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2017-05-01
卷号	467 期号:2 页码:1874-1889
关键词	binaries: close binaries: eclipsing stars: evolution stars: individual: EL CVn
ISSN号	0035-8711
通讯作者	Chen, Xuefei(Chinese Acad Sci, Yunnan Observ, Kunming 650011, Peoples R China)
产权排序	第1完成单位
英文摘要	EL CVn-type binaries are eclipsing binaries that contain an A-or F-type dwarf star and a very low mass (similar to 0.2 M-circle dot) helium white dwarf precursor (proto-He WD). A number of such objects have been discovered in the Wide Angle Search for Planets and Kepler photometric surveys. Here, we have studied the formation of EL CVn-type binaries and give the properties and the space density of this population of stars in the Galaxy. We show that EL CVn binaries cannot be produced by common envelope evolution as previously believed because this process leads to merging of the components when giants have such low-mass cores. Stable mass transfer in low-mass binaries, from more than 65 000 runs of Population I binary evolution, may well reproduce the properties of EL CVn stars such as the evolutionary phase, mass ratios and the WD mass-period (M-WD-P) relation. The study shows that the most common donor mass range for producing the observed EL CVn-type stars is 1.15-1.20 M-circle dot and that the lifetime of such objects increases dramatically with decreasing proto-He WD mass. This leads to an intrinsic peak mass around the minimum mass of proto-He WDs of similar to 0.16 M-circle dot. The most probable proto-He WD mass is 0.17-0.21 M-circle dot after selection effects included. We estimated the number of EL CVn stars with P <= 2.2 d to be 2-5 x 10(6) in the Galaxy, indicating a local density of 4-10 x 10(-6) pc-(3). We conclude that many more EL CVn-type binaries remain to be discovered and that these binaries will be predominantly low-mass systems in old stellar populations.
学科主题	天文学
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	STELLAR ASTROPHYSICS MESA ; WHITE-DWARF COMPANIONS ; RED-GIANT STAR ; LOW-MASS ; BLUE STRAGGLERS ; ORBITAL-PERIOD ; EVOLUTION ; SYSTEMS ; KEPLER ; PULSATIONS
收录类别	SCI
原文出处	https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx115
语种	英语
WOS记录号	WOS:000398416700046
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/10014]
专题	云南天文台_大样本恒星演化研究组云南天文台_中国科学院天体结构与演化重点实验室
作者单位	1.1Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China 2.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011, China 3.Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China 4.Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG, UK 5.University of the Chinese Academy of Sciences, Yuquan Road 19, Shijingshan Block, 100049 Beijing, China
推荐引用方式 GB/T 7714	Chen XF,Maxted, P. F. L.,Li J,et al. The formation of EL CVn-type binaries[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2017,467(2):1874-1889.
APA	Chen XF,Maxted, P. F. L.,Li J,&Han ZW.(2017).The formation of EL CVn-type binaries.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,467(2),1874-1889.
MLA	Chen XF,et al."The formation of EL CVn-type binaries".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 467.2(2017):1874-1889.