蓝色水平分支恒星大气中铁丰度的垂直分层
Vertical stratification of iron abundance in atmospheres of blue horizontal-branch stars
摘要：
观测到的某些蓝色水平分支（BHB）恒星的缓慢旋转和丰度特性表明，原子扩散在其恒星大气中可能很重要，并可能导致大气中化学物质的垂直丰度分层。为了验证这一假设，我们进行了丰度分层分析的基础上，最近获得的麦当劳CE光谱的大气中的六个BHB星。我们的数值模拟结果表明，在M15的两颗恒星：B267和B279的大气中，铁的丰度是垂直分层的。M13中的一颗恒星WF 2 -2541似乎也有垂直分层的铁丰度，而WF 4 -3085的铁分层特征则不那么令人信服。在所有的情况下，铁的丰度增加向低层大气。我们样本中的另外两颗恒星，WF 4 -3485和B84，没有显示出铁元素随大气深度的显著变化。我们的研究结果支持的想法，原子扩散占主导地位的其他流体动力学过程中的BHB星的大气。
英文摘要：
The observed slow rotation and abundance peculiarities of certain blue horizontal branch (BHB) stars suggests that atomic diffusion can be important in their stellar atmospheres and can lead to vertical abundance stratification of chemical species in the atmosphere. To verify this hypothesis, we have undertaken an abundance stratification analysis in the atmospheres of six BHB stars, based on recently acquired McDonald-CE spectra. Our numerical simulations show that the iron abundance is vertically stratified in the atmospheres of two stars in M15: B267 and B279. One star WF2-2541 in M13 also appears to have vertically stratified iron abundance, while for WF4-3085 the signatures of iron stratification are less convincing. In all cases the iron abundances increase towards the lower atmosphere. The other two stars in our sample, WF4-3485 and B84, do not show any significant variation of iron with atmospheric depth. Our results support the idea that atomic diffusion dominates other hydrodynamic processes in the atmospheres of BHB stars.
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