论文标题
改善光谱锂丰度。在不同金属性的FGK星中，3D非LTE校正的拟合功能
Improving spectroscopic lithium abundances. Fitting functions for 3D non-LTE corrections in FGK stars of different metallicity
论文作者
论文摘要
准确的光谱锂丰度对于解决各种空旷的问题至关重要，例如金属势力恒星（Spite Plateau）大气中均匀的锂含量的起源，或者存在于宿主星星的锂含量丰富之星的特性之间存在相关性。我们已经开发了一种工具，该工具使用户能够根据1D模型大气层提高标准锂丰度确定的准确性，并通过应用校正来说明流体动力学（3D）和非LTE（NLTE）在不同金属性的FGK恒星中效应。基于Co5bold 3D模型和相关的1D静水气氛的网格，我们计算了锂电平线的三个图库，用于670.8 nm的lithium线的合成光谱，分别计算出较宽的锂丰度，分别计算出3D NLTE，1D NLTE和1D LTE的详细线形成。然后，将所得的生长曲线用于得出3D NLTE和1D NLTE锂丰度校正。我们证明，对于高原上的金属贫困星而言，3D和NLTE效应很小，如果被忽略，则最多会导致+/- 0.05 DEX的误差。最大的校正是在最酷的有效温度下发现的，Teff = 5000 K，在其中最强的线可以达到-0.4 DEX。我们提出了用于评估校正并将给定锂丰度直接转化为同等宽度的分析函数，反之亦然，给定的当量宽度（EW）转化为锂丰度。为了方便起见，可以提供一个Python脚本，以评估给定TEFF，Log G，[Fe/H]和A（Li）或EW的所有拟合功能。通过拟合函数，使复杂的3D和NLTE计算的结果易于访问，并迅速适用于广泛的金属范围的大量恒星样本。
Accurate spectroscopic lithium abundances are essential in addressing a variety of open questions, such as the origin of a uniform lithium content in the atmospheres of metal-poor stars (Spite plateau) or the existence of a correlation between the properties of extra-solar planetary systems and the lithium abundance of their host stars. We have developed a tool that allows the user to improve the accuracy of standard lithium abundance determinations based on 1D model atmospheres and the assumption of Local Thermodynamic Equilibrium (LTE) by applying corrections that account for hydrodynamic (3D) and non-LTE (NLTE) effects in FGK stars of different metallicity. Based on a grid of CO5BOLD 3D models and associated 1D hydrostatic atmospheres, we computed three libraries of synthetic spectra of the lithium line at 670.8 nm for a wide range of lithium abundances, accounting for detailed line formation in 3D NLTE, 1D NLTE, and 1D LTE, respectively. The resulting curves-of-growth were then used to derive 3D NLTE and 1D NLTE lithium abundance corrections. We demonstrate that 3D and NLTE effects are small for metal-poor stars on the Spite plateau, leading to errors of at most +/-0.05 dex if ignored. The largest corrections are found at the coolest effective temperature, Teff=5000 K, where they can reach -0.4 dex for the strongest lines. We present analytical functions for evaluating the corrections and for directly converting a given lithium abundance into an equivalent width, or vice versa, a given equivalent width (EW) into a lithium abundance. For convenience, a Python script is made available that evaluates all fitting functions for given Teff, log g, [Fe/H], and A(Li) or EW. By means of the fitting functions, the results of complex 3D and NLTE calculations are made readily accessible and quickly applicable to large samples of stars across a wide range of metallicities.
