A search for Mg-poor stars using LAMOST survey data  

作　　者：Qian-Fan Xing Gang Zhao Yong Zhang Yong-Hui Hou Yue-Fei Wang Yue Wu 

机构地区：[1]Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences [2]University of Chinese Academy of Sciences [3]Nanjing Institute of Astronomical Optics & Technology,National Astronomical Observatories,Chinese Academy of Sciences

出　　处：《Research in Astronomy and Astrophysics》2015年第8期1275-1281,共7页天文和天体物理学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 11390371, 11233004, 11303040 and U1431106)

摘　　要：Most Galactic metal-poor stars exhibit enhanced α-abundances（e.g.[Mg/Fe] ～ ＋0.4） according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg（e.g. [Mg/Fe]～-0.2） show severe departures from this α-enhancement trend. The sub-solar[Mg/Fe] ratios of these anomalous stars indicate that they possess different chemical enrichment histories than the majority of Galactic metal-poor stars. In previous work,we presented a method to select Mg-poor metal-poor stars from low-resolution SDSS spectra based on a spectral matching technique. In this paper, a similar method is applied to low-resolution（R ～ 1800） LAMOST spectra. Stellar [Mg/Fe] abundances are determined by using stellar parameters delivered by the LAMOST Data Release2 catalog. From a sample of ～ 60 000 stars with atmospheric parameters in the range Teff = [5500, 6500] K and [Fe/H] = [-2.4, ＋0.5], we select 15 candidate Mg-poor metal-poor stars.Most Galactic metal-poor stars exhibit enhanced α-abundances（e.g.[Mg/Fe] ～ ＋0.4） according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg（e.g. [Mg/Fe]～-0.2） show severe departures from this α-enhancement trend. The sub-solar[Mg/Fe] ratios of these anomalous stars indicate that they possess different chemical enrichment histories than the majority of Galactic metal-poor stars. In previous work,we presented a method to select Mg-poor metal-poor stars from low-resolution SDSS spectra based on a spectral matching technique. In this paper, a similar method is applied to low-resolution（R ～ 1800） LAMOST spectra. Stellar [Mg/Fe] abundances are determined by using stellar parameters delivered by the LAMOST Data Release2 catalog. From a sample of ～ 60 000 stars with atmospheric parameters in the range Teff = [5500, 6500] K and [Fe/H] = [-2.4, ＋0.5], we select 15 candidate Mg-poor metal-poor stars.

关 键 词：methods： data analysis—stars： abundance—stars： atmospheres 

分 类 号：P148[天文地球—天体物理] TH751[天文地球—天文学]