论文标题
A-B星中Si I-II-III的非LTE线形成，以及Iota她的Si II排放线的起源
Non-LTE line formation for Si I-II-III in A-B stars and the origin of Si II emission lines in iota Her
论文作者
论文摘要
迄今为止，使用最新的原子数据为SI I-II-III开发了一个综合模型原子。基于SI I，SI II和SI II和SI III和高分辨率观察到的非本地热力学平衡（非LTE = NLTE）线的形成，我们确定了九个未加热的A9样品的NLTE丰度，该样品具有良好确定的大气参数。对于每个恒星，NLTE与LTE情况相比，NLTE大大降低了Si II的线对线散射，并导致不同电离阶段线的平均丰度一致。在我们样本中最热的恒星中，$ b her，si ii受到了监督，这会导致高兴奋（以上12.5 ev）二次级别产生的线排放。我们的NLTE计算在$ bh中重现了10条Si II排放线。同样的审理效应会导致SI II线大大削弱，这在她的$ $ $ $中被观察到。较大的正数丰度校正（5055 a的最高0.98 DEX）可用于实现两个电离阶段线的一致平均丰度，即SI II和SI III。发现SI II 6347，6371 A doublet in $ b y $ b her，NLTE效果被高估了，而新的模型原子对凉爽的恒星效果很好。在此阶段，我们未能理解这个问题。我们计算了在模型大气中的Si I，Si II和Si III线的NLTE丰度校正的网格，其有效温度和表面重力未发展的A-B型恒星的特征。
A comprehensive model atom was developed for Si I-II-III using the most up-to-date atomic data available so far. Based on the non-local thermodynamic equilibrium (non-LTE = NLTE) line formation for Si I, Si II, and Si III and high-resolution observed spectra, we determined the NLTE abundances for a sample of nine unevolved A9 to B3-type stars with well determined atmospheric parameters. For each star, NLTE reduces substantially the line-to-line scatter for Si II compared with the LTE case and leads to consistent mean abundances from lines of different ionisation stages. In the hottest star of our sample, $ι$ Her, Si II is subject to overionisation that drives emission in the lines arising from the high-excitation (above 12.5 eV) doublet levels. Our NLTE calculations reproduced 10 emission lines of Si II observed in $ι$ Her. The same overionisation effect leads to greatly weakened Si II lines, which are observed in absorption in $ι$ Her. Large positive NLTE abundance corrections (up to 0.98 dex for 5055 A) were useful for achieving consistent mean abundances from lines of the two ionisation stages, Si II and Si III. It was found that the NLTE effects are overestimated for the Si II 6347, 6371 A doublet in $ι$ Her, while the new model atom works well for the cooler stars. At this stage, we failed to understand this problem. We computed for a grid of the NLTE abundance corrections for lines of Si I, Si II, and Si III in the model atmospheres with effective temperatures and surface gravities characteristic of unevolved A-B type stars.
