Astronomy Letters ( IF 0.9 ) Pub Date : 2021-01-22 , DOI: 10.1134/s1063773720090054 M. D. Neretina , L. I. Mashonkina , T. M. Sitnova , S. A. Yakovleva , A. K. Belyaev
Abstract
We have constructed a new K I model atom using currently available atomic data. We have performed calculations for K I by abandoning the assumption of local thermodynamic equilibrium (non-LTE) for the Sun and three moderately metal-poor dwarf stars. To take into account the inelastic processes in collisions with hydrogen atoms, for the first time we have used the rate constants calculated by including the fine structure of K I levels and analyzed the influence of their application on the non-LTE results compared to the use of the rate constants calculated for combined levels. In agreement with the non-LTE studies available in the literature, K I is subject to overrecombination, which leads to a strengthening of spectral lines and negative abundance corrections. The non-LTE effects are shown to weaken when using new collisional data. We reached the same conclusion when comparing the non-LTE corrections calculated for the Ca II 8662 Å line in model atmospheres with \(\textrm{[Fe/H]}={-}4.5\) using the Ca II \(+\) H I collision rates derived with and without allowance for the fine structure of Ca II levels. However, the effect is very small for the other two triplet lines, Ca II 8498 and 8542 Å. The solar non-LTE abundance \(\log\varepsilon_{\textrm{K}}=5.09\pm 0.08\) derived from five lines is consistent with the meteoritic one within 0.01 dex. Despite the fact that in the atmospheres of the program stars the departures from LTE are larger than those in the Sun, the differential abundance [K/H] is almost independent of which collisional data set is used: the one calculated with or without allowance for the fine structure of K I levels.
中文翻译:
氢原子碰撞对恒星大气中KI和Ca II的非LTE效应的影响
摘要
我们使用当前可用的原子数据构造了一个新的K I模型原子。我们通过放弃太阳和三颗中等金属贫乏矮星的局部热力学平衡(非LTE)假设来进行KI计算。考虑到与氢原子碰撞时的非弹性过程,我们首次使用了速率常数,该速率常数是通过将KI能级的精细结构包括在内而计算出来的,并分析了它们的应用对非LTE结果的影响以及与LTE相比的影响。为组合水平计算的速率常数。与文献中可用的非LTE研究一致,K I受到过度重组的影响,这会导致光谱线增强和负丰度校正。当使用新的碰撞数据时,非LTE效应会减弱。\(\ textrm {[Fe / H]} = {-} 4.5 \)使用Ca II \(+ \) H I碰撞率,在有和没有Ca II能级精细结构的情况下得出。但是,对于其他两个三重态系Ca II 8498和8542Å,其影响很小。从五行得出的太阳非LTE丰度\(\ log \ varepsilon _ {\ textrm {K}} = 5.09 \ pm 0.08 \)与0.01 dex内的气象卫星一致。尽管在程序星的大气中,LTE的偏差要比太阳的偏差大,但差分丰度[K / H]几乎与所使用的碰撞数据集无关:计算的有无碰撞数据集KI级别的精细结构。