Stellar parameters of main sequence turn-off star candidates observed with LAMOST and Kepler
Ya-Qian Wu;Mao-Sheng Xiang;Xian-Fei Zhang;Tan-Da Li;Shao-Lan Bi;Xiao-Wei Liu;Jian-Ning Fu;Yang Huang;Zhi-Jia Tian;Kang Liu;Zhi-Shuai Ge;Xin He;Jing-Hua Zhang;Department of Astronomy, Beijing Normal University;National Astronomical Observatories, Chinese Academy of Sciences;Department of Astronomy, Peking University;
Main sequence turn-off(MSTO) stars have advantages as indicators of Galactic evolution since their ages can be robustly estimated from atmospheric parameters. Hundreds of thousands of MSTO stars have been selected from the LAMOST Galactic survey to study the evolution of the Galaxy,and it is vital to derive accurate stellar parameters. In this work, we select 150 MSTO star candidates from the MSTO star sample of Xiang that have asteroseismic parameters and determine accurate stellar parameters for these stars by combining asteroseismic parameters deduced from Kepler photometry and atmospheric parameters deduced from LAMOST spectra. With this sample, we examine the age determination as well as the contamination rate of the MSTO star sample. A comparison of age between this work and Xiang shows a mean difference of 0.53 Gyr(7%) and a dispersion of 2.71 Gyr(28%).The results show that 79 of the candidates are MSTO stars, while the others are contaminations from either main sequence or sub-giant stars. The contamination rate for the oldest stars is much higher than that for younger stars. The main cause for the high contamination rate is found to be the relatively large systematic bias in the LAMOST surface gravity estimates.
【Fund】： The Guoshoujing Telescope (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAMOST) is a National Major Scientific Project built by the Chinese Academy of Sciences;; provided by the National Development and Reform Commission;; National Astronomical Observatories Chinese Academy of Sciences;; supported by grants 11273007 and 10933002 from the National Natural Science Foundation of China;; the Joint Research Fund in Astronomy (U1631236) under cooperative agreement between the National Natural Science Foundation of China (NSFC) and Chinese Academy of Sciences (CAS);; the Fundamental Research Funds for the Central Universities;; Youth Scholars Program of Beijing Normal University
【CateGory Index】： P152
【CateGory Index】： P152