Searching for hot subdwarf stars from the LAMOST Spectra. II. Pure spectroscopic identification method for hot subdwarfs

被引：11

作者：

Lei, Zhenxin ^{[1
,2
]}

Bu, Yude ^{[3
]}

Zhao, Jingkun ^{[1
]}

Nemeth, Peter ^{[4
,5
]}

Zhao, Gang ^{[1
]}

机构：

[1] Chinese Acad Sci, Key Lab Opt Astron, Natl Astron Observ, Beijing 100012, Peoples R China

[2] Shaoyang Univ, Coll Sci, Shaoyang 422000, Peoples R China

[3] Shandong Univ, Sch Math & Stat, Weihai 264209, Shandong, Peoples R China

[4] Czech Acad Sci, Astron Inst, CZ-25165 Ondrejov, Czech Republic

[5] Astroserver Org, H-8533 Malomsok, Hungary

来源：

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN | 2019年 / 71卷 / 02期

基金：

中国国家自然科学基金;

关键词：

methods: miscellaneous; subdwarfs; surveys; HORIZONTAL-BRANCH STARS; DIGITAL SKY SURVEY; BLANKETED MODEL ATMOSPHERES; POSSIBLE FORMATION CHANNEL; EXTREME LEARNING-MACHINE; BLUE HOOK STARS; SUBLUMINOUS STARS; ULTRAVIOLET-RADIATION; WHITE-DWARFS; GALEX SURVEY;

D O I：

10.1093/pasj/psz006

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Employing a new machine-learning method, named the hierarchical extreme learning machine (HELM) algorithm, we identified 56 hot subdwarf stars in the first data release (DR1) of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) survey. The atmospheric parameters of the stars are obtained by fitting the profiles of hydrogen (H) Balmer lines and helium (He) lines with synthetic spectra calculated from non-local thermodynamic equilibrium (NLTE) model atmospheres. Five He-rich hot subdwarf stars were found in our sample with their log (nHe/nH) > -1, while 51 stars are He-poor sdB, sdO and sdOB stars. We also confirmed the two He sequences of hot subdwarf stars found by Edelmann et al. (2003, A&A, 400, 939) in a T-eff-log(nHe/nH) diagram. The HELM algorithm works directly on the observed spectroscopy and is able to filter out spectral properties without supplementary photometric data. The results presented in this study demonstrate that the HELM algorithm is a reliable method to search for hot subdwarf stars after suitable training is performed, and it can also be used to search for other objects which have obvious features in their spectra or images.

引用

页数：15

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