Bai Yu1; Luo Ali1; Comte Georges2; Zhao Jingkun1; Yang Haifeng1; Guo Yanxin1; Wang Youfen1; Li Yinbi1; Du Bing1; Hou Wen1; Kong Xiao1; Yi Zhenping3; Song Yihan1; Bai Zhongrui1; Zhang Jiannan1; Wang Mengxin1; Chen Jianjun1; Chen Xiaoyan1; Wu Kefei1; Zuo Fang1; Wu Yue1; Cao Zihuang1; Hou Yonghui4; Wang Yuefei4; Zhang Yong4
Source Publicationresearchinastronomyandastrophysics
AbstractWe identify 108 M subdwarfs (sdMs) out of more than two hundred thousand M type spectra from the second data release (DR2) of the LAMOST regular survey. This sample, among which 58 members are identified for the first time, includes 33 extreme subdwarfs (esdMs) and 11 ultra subdwarfs (usdMs). The selection is based on the usual ratio of absorption depth of CaH2, CaH3 and Ti05 band systems. We also emphasize the use of the CaH1 band. We provide estimates of spectral subtype (SPT),Lepine metallicity index ζ, effective temperature and Fe/H. Both ζ-Fe/H and SPT-T_(eff) figures show reasonable consistency; compared to PHOENIX model spectra, average rounded values of Fe/H for sdMs, esdMs and usdMs are respectively -0.5, -1 and -1.5. The photometric distances are estimated, indicating that most sources are located within 500 pc of the Sun and 350 pc of the Galactic disk. Velocities and 3D Galactic motions are also briefly discussed. Among the 108 subdwarfs, seven stars appear to be active with a significant Hα emission line. The source LAMOST J104521.52+482823.3 is a white dwarf - M subdwarf binary, while LAMOST J 123045.52+410943.8, also active, exhibits carbon features in red.
Document Type期刊论文
First Author AffilicationNational Astronomical Observatories, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
Bai Yu,Luo Ali,Comte Georges,et al. nearbymsubdwarfsfromlamostdatarelease2[J]. researchinastronomyandastrophysics,2016,16(7):107_01.
APA Bai Yu.,Luo Ali.,Comte Georges.,Zhao Jingkun.,Yang Haifeng.,...&Zhang Yong.(2016).nearbymsubdwarfsfromlamostdatarelease2.researchinastronomyandastrophysics,16(7),107_01.
MLA Bai Yu,et al."nearbymsubdwarfsfromlamostdatarelease2".researchinastronomyandastrophysics 16.7(2016):107_01.
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