A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

doi:10.1038/s41550-023-02188-2

	A seven-Earth-radius helium-burning star inside a 20.5-min detached binary
	Lin, Jie 2,18,19; Wu CY(吴程远)1,3,4; Xiong, Heran 5; Wang, Xiaofeng 14,18; Németh, Péter 15,16; Han ZW(韩占文)1,3,4; Li JD(李江丹)1,3; Elias-Rosa, Nancy 12,13; Salmaso, Irene 13,17; Filippenko, Alexei V.6
刊名	NATURE ASTRONOMY
	2024
ISSN号	2397-3366
DOI	10.1038/s41550-023-02188-2
产权排序	第4完成单位
文献子类	Article; Early Access
英文摘要	Binary evolution theory predicts that the second common envelope ejection can produce low-mass (0.32-0.36 M circle dot) subdwarf B (sdB) stars inside ultrashort-orbital-period binary systems, as their helium cores are ignited under nondegenerate conditions. With the orbital decay driven by gravitational-wave (GW) radiation, the minimum orbital periods of detached sdB binaries could be as short as similar to 20 min. However, only four sdB binaries with orbital periods below an hour have been reported so far, and none of them has an orbital period approaching the above theoretical limit. Here we report the discovery of a 20.5-min-orbital-period ellipsoidal binary, TMTS J052610.43+593445.1, in which the visible star is being tidally deformed by an invisible carbon-oxygen white dwarf companion. The visible component is inferred to be an sdB star with a mass similar to 0.33 M circle dot approaching the helium-ignition limit, although a He-core white dwarf cannot be completely ruled out. In particular, the radius of this low-mass sdB star is only 0.066 R circle dot, about seven Earth radii. Such a system provides a key clue in mapping the binary evolution scheme from the second common envelope ejection to the formation of AM CVn stars having a helium-star donor. It may also serve as a crucial verification binary of space-borne GW observatories such as LISA and TianQin in the future. A very uncommon detached binary system with a 20.5-min orbital period has been discovered to harbour a carbon-oxygen white dwarf star and a low-mass subdwarf B star with a seven-Earth radius that traces the theoretical limit of binary evolution predicted 20 years ago.
学科主题	天文学
URL标识	查看原文
出版地	HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY
资助项目	National Natural Science Foundation of China (NSFC)[12033003]; National Natural Science Foundation of China (NSFC)[12288102]; National Natural Science Foundation of China (NSFC)[11633002]; National Natural Science Foundation of China (NSFC)[202301AU070039]; Ma Huateng Foundation; New Cornerstone Science Foundation through the XPLORER PRIZE; China Manned-Spaced Project[CMS-CSST-2021-A12]; Scholar Program of the Beijing Academy of Science and Technology; Cyrus Chun Ying Tang Foundations; Yunnan Fundamental Research Projects[202302AN360001]; International Centre of Supernovae, Yunnan Key Laboratory[20179ZF5KS]; Grant Agency of the Czech Republic (GACR); Research Projects of National Relevance (PRIN) - Italian Ministry of Education, University and Research (MIUR)[NNX08AR22G]; Spanish Ministry of Science, Innovation and Universities[PID2020-112949GB-I00]; European Regional Development Fund; MIUR through PRIN 2017[NNX08AR22G]; MIUR through PRIN-INAF 2022; Istituto Nazionale di Astrofisica through the University of Padova; MIUR; Christopher R. Redlich Fund; GRANTECAN; National Plan of Astronomy and Astrophysics of the Spanish Government; US National Science Foundation (NSF)[22-34467S]; NASA[67985815]; NSF; MCIN/AEI/; European Union;
WOS关键词	LISA VERIFICATION BINARIES ; SUBDWARF-B-STARS ; LOW-MASS ; WHITE-DWARFS ; SDB STARS ; EVOLUTION ; TELESCOPE ; CHANNEL ; POPULATION ; KINEMATICS
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	NATURE PORTFOLIO
WOS记录号	WOS:001161147700002
资助机构	National Natural Science Foundation of China (NSFC)[12033003, 12288102, 11633002, 202301AU070039] ; Ma Huateng Foundation ; New Cornerstone Science Foundation through the XPLORER PRIZE ; China Manned-Spaced Project[CMS-CSST-2021-A12] ; Scholar Program of the Beijing Academy of Science and Technology ; Cyrus Chun Ying Tang Foundations ; Yunnan Fundamental Research Projects[202302AN360001] ; International Centre of Supernovae, Yunnan Key Laboratory[20179ZF5KS] ; Grant Agency of the Czech Republic (GACR) ; Research Projects of National Relevance (PRIN) - Italian Ministry of Education, University and Research (MIUR)[NNX08AR22G] ; Spanish Ministry of Science, Innovation and Universities[PID2020-112949GB-I00] ; European Regional Development Fund ; MIUR through PRIN 2017[NNX08AR22G] ; MIUR through PRIN-INAF 2022 ; Istituto Nazionale di Astrofisica through the University of Padova ; MIUR ; Christopher R. Redlich Fund ; GRANTECAN ; National Plan of Astronomy and Astrophysics of the Spanish Government ; US National Science Foundation (NSF)[22-34467S] ; NASA[67985815] ; NSF ; MCIN/AEI/ ; European Union ; [12003013] ; [PID2019-108709GB-I00] ; [AST-1440341] ; [AST-1238877] ; [776403] ; [BS202002]
内容类型	期刊论文
版本	出版稿
源URL	[http://ir.ynao.ac.cn/handle/114a53/26427]
专题	云南天文台_大样本恒星演化研究组
作者单位	1.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming, People’s Republic of China; 2.School of Astronomy and Space Sciences, University of Science and Technology of China, Hefei, People’s Republic of China; 3.Yunnan Observatories, Chinese Academy of Sciences, Kunming, People’s Republic of China; 4.International Centre of Supernovae, Yunnan Key Laboratory, Kunming, People’s Republic of China; 5.Research School of Astronomy & Astrophysics, Australian National University, Canberra, Australia; 6.Department of Astronomy, University of California, Berkeley, Berkeley, USA; 7.School of Physical Science and Technology, Xinjiang University, Urumqi, People’s Republic of China; 8.Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing, People’s Republic of China; 9.Department of Astronomy, Beijing Normal University, Beijing, People’s Republic of China; 10.National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China;
推荐引用方式 GB/T 7714	Lin, Jie,Wu CY,Xiong, Heran,et al. A seven-Earth-radius helium-burning star inside a 20.5-min detached binary[J]. NATURE ASTRONOMY,2024.
APA	Lin, Jie.,吴程远.,Xiong, Heran.,Wang, Xiaofeng.,Németh, Péter.,...&Li, Wenxiong.(2024).A seven-Earth-radius helium-burning star inside a 20.5-min detached binary.NATURE ASTRONOMY.
MLA	Lin, Jie,et al."A seven-Earth-radius helium-burning star inside a 20.5-min detached binary".NATURE ASTRONOMY (2024).