论文标题
FG型矮人中的3D非LTE铁丰度
3D non-LTE iron abundances in FG-type dwarfs
论文作者
论文摘要
铁丰度的光谱测量很容易出现系统的建模误差。我们在32个交错网格模型中介绍3D非LTE计算，其有效温度从5000 K到6500 K，表面重力为4.0 DEX和4.5 DEX，金属度从$ -3 DEX到0 DEX，并研究对171 FE I的影响，对171 FE I的影响和12 FE II光学线。在温暖的金属势恒星中，3D非LTE丰度高达0.5个DEX大于中间激发潜力的Fe I系的1D LTE丰度。相比之下，当使用低激发电位的Fe I线时，在凉爽的金属势力恒星中，3D非LTE丰度可能为0.2 dex。 3D非LTE和1D非LTE之间的相应丰度差异通常不那么严重，但仍然可以达到$ \ pm $ 0.2 DEX。对于Fe II线，3D丰度的范围从大于0.15的dex到0.10 dex，小于1D丰度，除了最低的金属度最高的恒星外，从3D LTE出发可忽略不计。结果使用基于神经网络的插值例程来纠正太阳和procyon（HD 61421）的一维LTE丰度（HD 61421），以及金属贫困恒星HD 84937和HD 140283。在所有四个恒星中，3D非LTE模型都达到了改善的电离平衡。在两个金属贫困的恒星中，它们消除了在有效温度下的激发失衡，相当于250 K至300 K误差。对于Procyon，3D非LTE模型建议[Fe/H] = 0.11 $ \ pm $ 0.03，它明显大于基于简单模型的文献值。除了公开提供FG型矮人的3D非LTE插值例程外，除了对FGKM型矮人和巨人的标准MARCS模型的一维非LTE出发系数外。从2019年开始，这些工具以及FE II的扩展3D LTE网格可以帮助提高晚期型星的恒星参数和铁丰度测定的准确性。
Spectroscopic measurements of iron abundances are prone to systematic modelling errors. We present 3D non-LTE calculations across 32 STAGGER-grid models with effective temperatures from 5000 K to 6500 K, surface gravities of 4.0 dex and 4.5 dex, and metallicities from $-$3 dex to 0 dex, and study the effects on 171 Fe I and 12 Fe II optical lines. In warm metal-poor stars, the 3D non-LTE abundances are up to 0.5 dex larger than 1D LTE abundances inferred from Fe I lines of intermediate excitation potential. In contrast, the 3D non-LTE abundances can be 0.2 dex smaller in cool metal-poor stars when using Fe I lines of low excitation potential. The corresponding abundance differences between 3D non-LTE and 1D non-LTE are generally less severe but can still reach $\pm$0.2 dex. For Fe II lines the 3D abundances range from up to 0.15 dex larger, to 0.10 dex smaller, than 1D abundances, with negligible departures from 3D LTE except for the warmest stars at the lowest metallicities. The results were used to correct 1D LTE abundances of the Sun and Procyon (HD 61421), and of the metal-poor stars HD 84937 and HD 140283, using an interpolation routine based on neural networks. The 3D non-LTE models achieve an improved ionisation balance in all four stars. In the two metal-poor stars, they remove excitation imbalances that amount to 250 K to 300 K errors in effective temperature. For Procyon, the 3D non-LTE models suggest [Fe/H] = 0.11 $\pm$ 0.03, which is significantly larger than literature values based on simpler models. We make the 3D non-LTE interpolation routine for FG-type dwarfs publicly available, in addition to 1D non-LTE departure coefficients for standard MARCS models of FGKM-type dwarfs and giants. These tools, together with an extended 3D LTE grid for Fe II from 2019, can help improve the accuracy of stellar parameter and iron abundance determinations for late-type stars.
