Extremely metal-poor stars CaII triplet

We extend our previous calibration of the infrared CaII triplet (CaT) as a metallicity indicator to the metal-poor regime by including observations of 55 field stars with [Fe/H]...我们将此前将红外CaII三线谱（infrared CaII triplet，CaT）作为金属丰度指示剂的定标工作，拓展至贫金属参数区间，新增纳入了55颗[Fe/H]……的场星观测数据。