Red clump stars from the LAMOST dataⅠ: identification and distance

作     者：Jun-Chen Wan Chao Liu Li-Cai Deng Wen-Yuan Cui Yong Zhang Yong-Hui Hou Ming Yang Yue Wu 

作者机构：Key Laboratory of Optical AstronomyNational Astronomical ObservatoriesChinese Academy of Sciences Physics DepartmentHebei Normal University Nanjing Institute of Astronomical Optics & TechnologyNational Astronomical ObservatoriesChinese Academy of Sciences 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2015年第15卷第8期

页      面：1166-1181页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：supported by the Strategic Priority Research Program "The Emergence of Cosmological Structures" of the Chinese Academy of Sciences (Grant No. XDB09000000) the National Key Basic Research Program of China (2014CB845700) CL acknowledges the National Natural Science Foundation of China (NSFC, Grant Nos. 11373032, 11333003 and U1231119) 

主　　题：stars: general—stars: horizontal branch—stars: statistics—stars: distances—Galaxy: stellar content 

摘      要：We present a sample of about 120 000 red clump candidates selected from the LAMOST DR2 catalog based on the empirical distribution model in the effective temperature vs. surface gravity plane. Although, in general, red clump stars are considered as standard candles, they do not exactly stay in a narrow range of absolute magnitude, but may have a range of more than one magnitude depending on their initial mass. Consequently, conventional oversimplified distance estimations with the assumption of a fixed luminosity may lead to systematic bias related to the initial mass or age, which can potentially affect the study of the evolution of the Galaxy with red clump stars. We therefore employ an isochrone-based method to estimate the absolute magnitude of red clump stars from their observed surface gravities, effective temperatures and metallicities. We verify that the estimation removes the systematics well and provides initial mass/age estimates that are independent of distance with accuracy better than 10%.