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The Formation of Subdwarf A-type Stars
Yu, Jinlong1; Li ZW(李振威)2,3,4; Zhu, Chunhua1; Wang, Zhaojun1; Liu, Helei1; Guo, Sufen1; Han ZW(韩占文)2,3,4,5; Chen XF(陈雪飞)2,3,5; Lü, Guoliang1
Source PublicationThe Astrophysical Journal
Contribution Rank第2完成单位
Indexed BySCI
Keywordbinaries: close stars: fundamental parameters white dwarfs

Abstract Subdwarf A-type stars (sdAs) are objects that have hydrogen-rich spectra with surface gravity similar to that of hot subdwarf stars but effective temperature below the zero-age horizontal branch. They are considered to be metal-poor main-sequence (MS) stars or extremely low-mass white dwarfs (ELM WDs). In this work, using the stellar evolution code Modules for Experiments in Stellar Astrophysics, we investigate the sdAs formed both by the evolution of (pre-)ELM WDs in double-degenerate systems and metal-poor MS stars with single evolution models. We find that both of the evolutionary tracks of ELM WDs and metal-poor MS stars can explain the observation properties of sdAs. However, the proportions between these two populations are uncertain. In this work, we adopt the method of binary population synthesis of both ELM WDs in the disk and metal-poor MS stars in the halo to obtain their populations at different stellar population ages and calculate their proportions. We find that the proportion of metal-poor MS stars to sdAs for a stellar population of 10 Gyr is ~98.5%, which is consistent with the conclusion that most sdAs (>95%) are metal-poor MS stars. And the proportion of ELM WDs (metal-poor MS stars) to sdAs increases (decreases) from 0.1% (99.9%) to 20% (80%) with stellar population ages from 5 to 13.7 Gyr.

Subject Area天文学 ; 恒星与银河系 ; 恒星物理学 ; 恒星形成与演化
MOST Discipline Catalogue理学 ; 理学::天文学
PublisherThe American Astronomical Society
WOS IDIOP:0004-637X-885-1-ab44b5
Citation statistics
Document Type期刊论文
Affiliation1.School of Physical Science and Technology, Xinjiang University, Urumqi, 830046, People's Republic of China
2.Yunnan Observatories, Chinese Academy of Sciences, Kunming, 650011, People's Republic of China
3.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Science, People's Republic of China
4.University of the Chinese Academy of Science, Yuquan Road 19, Shijingshan Block, 100049, Beijing, People's Republic of China
5.Center for Astronomical Mega-Science, Chinese Academy of Science, 20A Datun Road, Chaoyang District, Beijing 100012, People's Republic of China
Recommended Citation
GB/T 7714
Yu, Jinlong,Li ZW,Zhu, Chunhua,et al. The Formation of Subdwarf A-type Stars[J]. The Astrophysical Journal,2019,885(1).
APA Yu, Jinlong.,Li ZW.,Zhu, Chunhua.,Wang, Zhaojun.,Liu, Helei.,...&Lü, Guoliang.(2019).The Formation of Subdwarf A-type Stars.The Astrophysical Journal,885(1).
MLA Yu, Jinlong,et al."The Formation of Subdwarf A-type Stars".The Astrophysical Journal 885.1(2019).
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