M dwarf stars—the by-product of X-ray selected AGN candidates  

作　　者：Yu Bai Yan-Chun Suni Xiang-Tao Hei Yang Chen Jiang-Hua Wui Qing-Kang Li Richard F. Green Wolfgang Voges 

机构地区：[1]Department of Astronomy, Beijing Normal University, Beijing 100875, China [2]Kitt Peak National Observatory, NOAO, Tucson, AZ 85726-6732, USA [3]Max-Planck-Institute fur Extraterrestrische Physik, D-85740 Garching, Germany

出　　处：《Research in Astronomy and Astrophysics》2012年第4期443-452,共10页天文和天体物理学研究（英文版）

基　　金：supported by the Scientific Research Foundation of Beijing Normal University;the National Natural Science Foundation of China (Grant No.10778717);supported by the Open Project Program of the Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences

摘　　要：X-ray loud M dwarfs are a major source of by-products （contamination） in the X-ray band of the multiwavelength quasar survey. As a by-product, the low dispersion spectra of 22 M dwarfs are obtained in which the spectra of 16 sources are taken for the first time. The spectral types and distances of the sample are given based on spectral indices CaH2, CaH3, and TiO5. The parameter ζ TiO/CaH is calculated to separate the different metallicity classes among dwarfs, subdwarfs and extreme subdwarfs. We also discuss the distributions in the diagrams of log（L x /L bol ）, the ratio between X-ray and bolometric luminosity versus spectral type and infrared colors.X-ray loud M dwarfs are a major source of by-products （contamination） in the X-ray band of the multiwavelength quasar survey. As a by-product, the low dispersion spectra of 22 M dwarfs are obtained in which the spectra of 16 sources are taken for the first time. The spectral types and distances of the sample are given based on spectral indices CaH2, CaH3, and TiO5. The parameter ζ TiO/CaH is calculated to separate the different metallicity classes among dwarfs, subdwarfs and extreme subdwarfs. We also discuss the distributions in the diagrams of log（L x /L bol ）, the ratio between X-ray and bolometric luminosity versus spectral type and infrared colors.

关 键 词：spectroscopic — stars： X-rays： M dwarfs 

分 类 号：P145.5[天文地球—天体物理] O434.1[天文地球—天文学]