Post-merger evolution of carbon-oxygen plus helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars

	Post-merger evolution of carbon-oxygen plus helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars
	Zhang, XF 1; Jeffery, CS 1,2; Chen XF(陈雪飞)3,4 ; Han ZW(韩占文)3,4 ; Zhang, Xianfei
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2014-11-21
卷号	445 期号:1 页码:660-673
关键词	stars: abundances binaries: close stars: evolution white dwarfs
ISSN号	0035-8711
通讯作者	Zhang, XF (reprint author), Armagh Observ, Coll Hill, Armagh BT61 9DG, North Ireland.
产权排序	第三完成单位
英文摘要	Orbital decay by gravitational-wave radiation will cause some close-binary white dwarfs (WDs) to merge within a Hubble time. The results from previous hydrodynamical WD-merger simulations have been used to guide calculations of the post-merger evolution of carbon-oxygen + helium (CO+He) WD binaries. Our models include the formation of a hot corona in addition to a Keplerian disc. We introduce a 'destroyed-disc' model to simulate the effect of direct disc ingestion into the expanding envelope. These calculations indicate significant lifetimes in the domain of the rare R Coronae Borealis (RCB) stars, before a fast evolution through the domain of the hotter extreme helium (EHe) stars. Surface chemistries of the resulting giants are in partial agreement with the observed abundances of RCB and EHe stars. The production of He-3, O-18 and F-19 are discussed. Evolutionary time-scales combined with binary WD merger rates from binary-star population synthesis are consistent with present-day numbers of RCBs and EHes, provided that the majority come from relatively recent (<2 Gyr) star formation. However, most RCBs should be produced by CO-WD + low-mass He-WD mergers, with the He WD having a mass in the range 0.20-0.35 M-circle dot. Whilst, previously, a high He-WD mass (>= 0.40 M-circle dot) was required to match the carbon-rich abundances of RCB stars, the 'destroyed-disc' model yields a high-carbon product with He-WD mass >= 0.30 M-circle dot, in better agreement with population synthesis results.
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]	HYDROGEN-DEFICIENT CARBON ; DOUBLE-DEGENERATE MERGER ; INTERMEDIATE-MASS STARS ; STELLAR EVOLUTION ; STRANGE MODES ; NUCLEOSYNTHESIS ; ABUNDANCES ; METALLICITY ; PULSATIONS ; SOLAR
收录类别	SCI
原文出处	http://mnras.oxfordjournals.org/content/445/1/660
语种	英语
WOS记录号	WOS:000343827700049
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/4568]
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
通讯作者	Zhang, Xianfei
作者单位	1.Armagh Observatory, College Hill, Armagh BT61 9DG, UK 2.School of Physics, Trinity College Dublin, Dublin 2, Ireland 3.Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China 4.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011, People's Republic of China
推荐引用方式 GB/T 7714	Zhang, XF,Jeffery, CS,Chen XF,et al. Post-merger evolution of carbon-oxygen plus helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2014,445(1):660-673.
APA	Zhang, XF,Jeffery, CS,Chen XF,Han ZW,&Zhang, Xianfei.(2014).Post-merger evolution of carbon-oxygen plus helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,445(1),660-673.
MLA	Zhang, XF,et al."Post-merger evolution of carbon-oxygen plus helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 445.1(2014):660-673.