A self-consistent chemically stratified atmosphere model for the roAp star 10 Aquilae
A self-consistent chemically stratified atmosphere model for the roAp star 10 Aquilae
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DOI：
10.1051/0004-6361/201220320
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发表时间：
2012-12
影响因子：
6.5
通讯作者：
N. Nesvacil;D. Shulyak;T. Ryabchikova;O. Kochukhov;A. Akberov;W. Weiss
中科院分区：
文献类型：
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作者：
N. Nesvacil;D. Shulyak;T. Ryabchikova;O. Kochukhov;A. Akberov;W. Weiss
上下文化学奇特A型（Ap）星是CP 2星的一个亚群，表现出许多元素的异常丰度，例如Fe，Cr，Sr和稀土元素。脉动子群的Ap星，roAp星，目前理想的实验室，以观察和模拟脉动签名，以及相互作用的脉动与强磁场和垂直丰度梯度。目标。基于高分辨率光谱观测和观测到的恒星能量分布，我们构造了天鹰座星星10（HD 176232）的自洽大气模型。它解释了垂直丰度梯度引起的温压结构的调制。我们证明，这样的分析可以用来精确地确定脉动建模所需的基本大气参数。方法.平均丰度为56种。对于Mg，Si，Ca，Cr，Fe，Co，Sr，Pr和Nd，垂直分层配置文件是经验性地使用DDAFIT最小化例程与磁谱合成代码SYNTHMAG一起导出的。模型大气是用LLMODELS代码计算的，该代码解释了化学元素的个体丰度和分层。结果对于最终模型大气，采用T-eff = 7550 K和log（g）= 3.8。虽然Mg、Si、Co和Cr表现出陡峭的丰度梯度，但Ca、Fe和Sr表现出在log tau（5000）= -1.5和0.5之间宽得多的丰度梯度。元素镁和钴被认为是分层最少，而钙和锶表现出强烈的深度变化的丰度高达约6德克斯。
Context. Chemically peculiar A-type (Ap) stars are a subgroup of the CP2 stars that exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr, and rare earth elements. The pulsating subgroup of Ap stars, the roAp stars, present ideal laboratories to observe and model pulsational signatures, as well as the interplay of the pulsations with strong magnetic fields and vertical abundance gradients. Aims. Based on high-resolution spectroscopic observations and observed stellar energy distributions, we construct a self-consistent model atmosphere for the roAp star 10 Aquilae (HD 176232). It accounts for modulations of the temperature-pressure structure caused by vertical abundance gradients. We demonstrate that such an analysis can be used to determine precisely the fundamental atmospheric parameters required for pulsation modelling. Methods. Average abundances were derived for 56 species. For Mg, Si, Ca, Cr, Fe, Co, Sr, Pr, and Nd, vertical stratification profiles were empirically derived using the DDAFIT minimisation routine together with the magnetic spectrum synthesis code SYNTHMAG. Model atmospheres were computed with the LLMODELS code, which accounts for the individual abundances and stratification of chemical elements. Results. For the final model atmosphere, T-eff = 7550 K and log (g) = 3.8 were adopted. While Mg, Si, Co, and Cr exhibit steep abundance gradients, Ca, Fe, and Sr showed much wider abundance gradients between log tau(5000) = -1.5 and 0.5. Elements Mg and Co were found to be the least stratified, while Ca and Sr showed strong depth variations in abundance of up to approximate to 6 dex.