Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. V. On the Origin of the "Young" [alpha/Fe]-enhanced Stars | |
Sun, W. -X.2; Huang, Y.2; Wang, H. -F.2; Wang, C.1,4; Zhang, M.1,4; Li, X. -Y.2; Chen, B. -Q.2; Zhang, H. -W.1,4; Wei DD(魏丹丹)3; Jiang DK(姜登凯)3 | |
刊名 | ASTROPHYSICAL JOURNAL |
2020-11-01 | |
卷号 | 903期号:1页码:10 |
关键词 | Galaxy chemical evolution Galaxy structure Stellar abundances Galaxy stellar disks Stellar kinematics |
ISSN号 | 0004-637X |
DOI | 10.3847/1538-4357/abb1b7 |
产权排序 | 第4完成单位 |
文献子类 | Article |
英文摘要 | Using a sample of nearly 140,000 primary red-clump stars selected from the LAMOST and Gaia surveys, we have identified a large sample of "young" [alpha/Fe]-enhanced stars with stellar ages younger than 6.0 Gyr and [alpha/Fe] ratios greater than 0.15 dex. The stellar ages and [alpha/Fe] ratios are measured from LAMOST spectra, using a machine-learning method trained with common stars in the LAMOST-APOGEE fields (for [alpha/Fe]) and in the LAMOST-Kepler fields (for stellar age). The existence of these "young" [alpha/Fe]-enhanced stars is not expected from the classical Galactic chemical evolution models. To explore their possible origins, we have analyzed the spatial distribution, and the chemical and kinematic properties of those stars and compared the results with those of the chemically thin and thick disk populations. We find that those "young" [alpha/Fe]-enhanced stars have distributions in number density, metallicity, [C/N] abundance ratio, velocity dispersion, and orbital eccentricity that are essentially the same as those of the chemically thick disk population. Our results clearly show those so-called "young" [alpha/Fe]-enhanced stars are not really young but genuinely old. Although other alternative explanations can not be fully ruled out, our results suggest that the most possible origin of these old stars is the result of stellar mergers or mass transfer. |
学科主题 | 天文学 ; 星系与宇宙学 ; 星系形成与演化 ; 恒星与银河系 ; 恒星形成与演化 |
URL标识 | 查看原文 |
出版地 | TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND |
资助项目 | National Key R&D Program of China[2019YFA0405500] ; National Natural Science Foundation of China[11903027] ; National Natural Science Foundation of China[11973001] ; National Natural Science Foundation of China[11833006] ; National Natural Science Foundation of China[U1731108] ; National Natural Science Foundation of China[117733008] ; National Natural Science Foundation of China[12073070] ; National Natural Science Foundation of China[12003027] ; Yunnan University[C176220100006] ; China Postdoctoral Science Foundation[2019M653504] ; China Postdoctoral Science Foundation[2020T130563] ; Yunnan province postdoctoral Directed culture Foundation ; National Development and Reform Commission ; Chinese Academy of Sciences ; Chinese Academy of Sciences (CAMS) |
WOS关键词 | LOCAL STANDARD ; GALAH SURVEY ; MILKY ; THICK ; ROTATION ; MOTION ; AGES ; MASS ; HALO |
WOS研究方向 | Astronomy & Astrophysics |
语种 | 英语 |
出版者 | IOP PUBLISHING LTD |
WOS记录号 | WOS:000583990100001 |
资助机构 | National Key R&D Program of China[2019YFA0405500] ; National Natural Science Foundation of China[11903027, 11973001, 11833006, U1731108, 117733008, 12073070, 12003027] ; Yunnan University[C176220100006] ; China Postdoctoral Science Foundation[2019M653504, 2020T130563] ; Yunnan province postdoctoral Directed culture Foundation ; National Development and Reform Commission ; Chinese Academy of Sciences ; Chinese Academy of Sciences (CAMS) |
内容类型 | 期刊论文 |
源URL | [http://ir.ynao.ac.cn/handle/114a53/23858] |
专题 | 云南天文台_大样本恒星演化研究组 |
通讯作者 | Huang, Y.; Wang, H. -F.; Liu, X. -W. |
作者单位 | 1.Department of Astronomy, Peking University, Beijing 100871, People's Republic of China 2.South-Western Institute for Astronomy Research, Yunnan University, Kunming 650500, People's Republic of China 3.Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011, People's Republic of China 4.Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People's Republic of China |
推荐引用方式 GB/T 7714 | Sun, W. -X.,Huang, Y.,Wang, H. -F.,et al. Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. V. On the Origin of the "Young" [alpha/Fe]-enhanced Stars[J]. ASTROPHYSICAL JOURNAL,2020,903(1):10. |
APA | Sun, W. -X..,Huang, Y..,Wang, H. -F..,Wang, C..,Zhang, M..,...&Liu, X. -W..(2020).Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. V. On the Origin of the "Young" [alpha/Fe]-enhanced Stars.ASTROPHYSICAL JOURNAL,903(1),10. |
MLA | Sun, W. -X.,et al."Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. V. On the Origin of the "Young" [alpha/Fe]-enhanced Stars".ASTROPHYSICAL JOURNAL 903.1(2020):10. |
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