M-subdwarf Research. I. Identification, Modified Classification System, and Sample Construction

doi:10.3847/1538-4365/aafb32

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	M-subdwarf Research. I. Identification, Modified Classification System, and Sample Construction
	Zhang,Shuo 1,2; Luo,A-Li 1,2; Comte,Georges 3; Gizis,John E.4; Wang,Rui 1,2; Li,Yinbi 1; Qin,Li 2; Kong,Xiao 1,2; Bai,Yu 1; Yi,Zhenping 5
刊名	The Astrophysical Journal Supplement Series
	2019-02-06
卷号	240 期号:2
关键词	stars: late-type stars: low-mass stars: statistics subdwarfs
ISSN号	0067-0049
DOI	10.3847/1538-4365/aafb32
英文摘要	Abstract We propose a revision of the system developed by Lépine et al. for spectroscopic M-subdwarf classification. Based on an analysis of subdwarf spectra and templates from Savcheva et al., we show that the CaH1 feature originally proposed by Gizis is important in selecting reliable cool subdwarf spectra. This index should be used in combination with the [TiO5, CaH2+CaH3] relation provided by Lépine et al. to avoid misclassification results. In the new system, the dwarf–subdwarf separators are first derived from a sample of more than 80,000 M dwarfs and a “labeled” subdwarf subsample, and these objects are all visually identified from their optical spectra. Based on these two samples, we refit the initial [TiO5, CaH1] relation and propose a new [CaOH, CaH1] relation supplementing the [TiO5, CaH1] relation to reduce the impact of uncertainty in flux calibration on classification accuracy. In addition, we recalibrate the ζTiO/CaH parameter defined in Lépine et al. to enable its successful application to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. Using this new system, we select candidates from LAMOST Data Release 4 and finally identify a set of 2791 new M-subdwarf stars, covering the spectral sequence from type M0 to M7. This sample contains a large number of objects located at low Galactic latitudes, especially in the Galactic anti-center direction, expanding beyond previously published halo- and thick disk-dominated samples. Besides, we detect magnetic activity in 141 objects. We present a catalog for this M-subdwarf sample, including radial velocities, spectral indices and errors, and activity flags, with a compilation of external data (photometric and Gaia Data Release 2 astrometric parameters). The catalog is provided online, and the spectra can be retrieved from the LAMOST Data Release web portal.
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0067-0049-240-2-AAFB32
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/24927]
专题	中国科学院国家天文台
作者单位	1.Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, People's Republic of China lal@nao.cas.cn 2.University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China 3.Aix-Marseille Univ, CNRS, CNES, LAM, Laboratoire d’Astrophysique de Marseille, Marseille, France 4.Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA 5.School of Mechanical, Electrical and Information Engineering, Shandong University at Weihai, Weihai 264209, People's Republic of China
推荐引用方式 GB/T 7714	Zhang,Shuo,Luo,A-Li,Comte,Georges,et al. M-subdwarf Research. I. Identification, Modified Classification System, and Sample Construction[J]. The Astrophysical Journal Supplement Series,2019,240(2).
APA	Zhang,Shuo.,Luo,A-Li.,Comte,Georges.,Gizis,John E..,Wang,Rui.,...&Yi,Zhenping.(2019).M-subdwarf Research. I. Identification, Modified Classification System, and Sample Construction.The Astrophysical Journal Supplement Series,240(2).
MLA	Zhang,Shuo,et al."M-subdwarf Research. I. Identification, Modified Classification System, and Sample Construction".The Astrophysical Journal Supplement Series 240.2(2019).