基于APOGEE红外高分辨率光谱的重要元素NLTE效应研究

本研究课题的主要目标是利用斯隆APOGEE的高分辨率、高信噪比H波段红外光谱确定恒星的表面重力等基本参数，研究海量恒星中一些重要元素的丰度分布模式，进一步研究银河系恒星形成和化学演化的历史，了解这些元素的起源和第一代超新星的爆发过程。本项目的研究特色是：我们将在国际上首次考虑Mg、Si、Ca和Fe的H波段谱线受非局部热动平衡效应的影响，研究利用H波段Mg和Si的强线确定恒星的表面重力，考虑非局部热动平衡效应对金属丰度确定的影响。我们将进一步完善已建立的Mg、Si、Ca和Fe原子模型，使之可靠应用到H波段的高分辨率光谱分析方面，进一步建立考虑了非局部热动平衡效应的恒星模板库，精确确定海量恒星表面上述重要元素的丰度。研究银河系中不同星族、不同空间位置，特别是核球和银盘恒星的丰度分布模式，研究银河系的金属丰度梯度，核球和银盘的形成和化学演化历史。

The main purpose of this project is to determine the stellar parameters (surface gravity) for a large sample of APOGEE objects based on the high resolutin, high signal to noise H band spectra, and the abundance pattern of some important elements are derived for the sample stars, which will help us to understand the origin of these elements and the explosive nucleosynthesis of first generation SN II, also the star formation hsitory and chemical evolution of our Galaxy. We will investigate the NLTE effects of Mg, Si, Ca and Fe H band lines firstly in the world, and we will examine how to determine the surface gravity based on the strong Mg and Si lines. We will extend our Mg, Si, Ca and Fe atomic models to the H band lines, and further to set up the standard template library in order to determine the abundances of above elements for huge stars, the NLTE effects are included in the analyses. We can learn the abundance patterns for the differnet populations, especially for the stars in the bulge and inner disk.