NLTE Analysis of High-Resolution H-Band Spectra, V: Neutral Sodium
NLTE Analysis of High-Resolution H-Band Spectra, V: Neutral Sodium
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DOI：
10.3390/universe9110457
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发表时间：
2023-10
期刊：
影响因子：
2.9
通讯作者：
Ze-Ming Zhou;Jianrong Shi;Shaolan Bi;Hongliang Yan;Junbo Zhang;K. Pan;Xiaodong Xu
中科院分区：
文献类型：
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作者：
Ze-Ming Zhou;Jianrong Shi;Shaolan Bi;Hongliang Yan;Junbo Zhang;K. Pan;Xiaodong Xu
为了推导钠丰度并研究非局域热力学平衡 (NLTE) 对 H 带 Na I 线形成的影响，我们通过结合新量子力学计算中与氢的碰撞率来更新钠原子模型。通过分析阿帕奇点天文台银河演化实验 (APOGEE) 的高分辨率 H 波段光谱以及局部热力学平衡 (LTE) 和 NLTE 条件下的光谱，获得了 13 颗样本恒星的差异 Na 丰度。两个能带的一致丰度表明我们更新的原子模型对于研究 H 能带 Na I 线的形成是有效的。我们的计算表明，在我们的恒星参数空间中，NLTE 效应是负的，并且可能导致光学线路上的修正大于 -0.4 dex。 H 波段 Na I 线的校正通常很小，大约在 0.05 dex 内，但如果需要准确的钠丰度，则不可忽略。我们注意到 [Na/Fe] 比率有利于理论星系化学模型。
In order to derive sodium abundances and investigate the effects of non-local thermodynamic equilibrium (NLTE) on the formation of H-band Na I lines, we update the sodium atomic model by incorporating collision rates with hydrogen from new quantum-mechanical calculations. The differential Na abundances for 13 sample stars are obtained by analyzing high-resolution H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and optical spectra under both local thermodynamic equilibrium (LTE) and NLTE conditions. Consistent abundances from both bands suggest that our updated atomic model is valid for studying the formation of H-band Na I lines. Our calculations show that, in our stellar parameter space, NLTE effects are negative and can result in corrections larger than −0.4 dex on optical lines. The corrections on H-band Na I lines are typically small, within about 0.05 dex, but not negligible if accurate sodium abundance is desired. We note that the [Na/Fe] ratios favor the theoretical galactic chemical model.