Fundamental parameters of bright Ap stars from wide-range energy distributions and advanced atmospheric models
Fundamental parameters of bright Ap stars from wide-range energy distributions and advanced atmospheric models
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来自大范围能量分布和先进大气模型的明亮 Ap 星的基本参数
DOI：
10.1051/0004-6361/201220425
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发表时间：
2012
影响因子：
6.5
通讯作者：
O. Kochukhov
中科院分区：
文献类型：
--
作者：
D. Shulyak;T. Ryabchikova;O. Kochukhov
目标。对于大多数正常主序星来说，大气和恒星参数的测定是一个行之有效的方法，但对于磁性化学特殊的恒星来说，这是一个具有挑战性的过程。化学元素的不均匀分布和强磁场使得大多数标准的光度和光谱校准不适用于这类恒星。在这项工作中，我们利用现有的观测到的能量分布校准到绝对单位，恒星的光，高分辨率的光谱观测，和先进的恒星大气模型，以获得三个明亮的Ap星的参数：33 Lib，伽马Equ，和β CrB。方法.模式大气和通量计算与LLmodels代码。SYNTH3和SYNTHMAG代码用于计算丰度分析中涉及的各个谱线的剖面。结果对于每一颗恒星，我们构建了一个自洽的大气模型，假设正常和耗尽氦成分，并得出经验分层配置文件的某些元素。有效的温度和表面重力，发现从同时适合光谱，光度，和分光光度观测校准到绝对单位。我们表明，使用先进的模型大气和准确的恒星半径可以得到恒星半径具有高精度，这些是一致的，从独立的，但更复杂的干涉观测。
Aims. As a well-established procedure for the vast majority of normal main-sequence stars, determination of atmospheric and stellar parameters turns to be a challenging process in case of magnetic chemically peculiar stars. Inhomogeneous distribution of chemical elements and strong magnetic fields make most of the standard photometric and spectroscopic calibrations inapplicable for this class of stars. In this work we make use of available observed energy distributions calibrated to absolute units, stellar parallaxes, high-resolution spectroscopic observations, and advanced stellar atmosphere models to derive parameters of three bright Ap stars: 33 Lib, gamma Equ, and beta CrB. Methods. Model atmospheres and fluxes were computed with the LLmodels code. SYNTH3 and SYNTHMAG codes were used to compute profiles of individual spectral lines involved in abundance analysis. Results. For each of the stars, we construct a self-consistent atmospheric models assuming normal and depleted helium compositions and derive empirically stratification profiles of certain elements. The effective temperatures and surface gravities are found from the simultaneous fit to spectroscopic, photometric, and spectrophotometric observations calibrated to absolute units. We show that using advanced model atmospheres and accurate stellar parallaxes allows one to derive stellar radii with high accuracy, and these are consistent with those obtained from independent but more complicated interferometric observations.