Spectrum synthesis for radially pulsating stars with shocked atmospheres
Spectrum synthesis for radially pulsating stars with shocked atmospheres
复制标题
具有冲击大气的径向脉动恒星的光谱合成
DOI：
10.1093/mnras/stac1644
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发表时间：
2022
影响因子：
4.8
通讯作者：
Jeffery C
中科院分区：
文献类型：
--
作者：
Jeffery C
spec_tool描述了一套计算机程序来模拟径向脉动星星的出射光谱。它结合了克里斯蒂型非线性脉动代码与经典的恒星大气代码。主要目的是解释径向脉动的极端氦星星V652武仙座（V652 Her）的动力学谱，它显示了在最小半径处的强激波。这些部件足够通用，可以处理其他类别的径向脉动。从一个冲击脉动模型的理论频谱显示线加倍，与蓝色分量出现在静止速度和加速蓝向。倍增相位取决于谱线深度和母离子。线核心的行为后冲击点的电离温度下降，虽然在模型中的气体温度仍然很高。激波压缩导致斯塔克加宽线翼的相位相关强化，远翼首先响应。通过速度、温度和压力敏感诊断，V652 Her中脉冲驱动冲击的详细断层扫描似乎是可能的。即使在没有激波的情况下，动力学谱也与流体静力平衡模式有很大的不同。使用准静态近似（例如在最大半径）可能会导致大大低估星星的平均有效温度和表面重力。
spec_pulsdescribes a suite of computer programs to simulate the emergent spectrum from a radially pulsating star. It combines a Christy-type non-linear pulsation code with classical stellar atmosphere codes. The principal aim is to interpret the dynamical spectrum of the radially pulsating extreme helium star V652 Herculis (V652 Her), which shows a strong shock at minimum radius. The components are general enough to treat other classes of radial pulsation. The theoretical spectrum from a shocked pulsation model shows line doubling, with the blue component emerging at standstill velocity and accelerating blueward. The doubling phase depends on line depth and parent ion. The behaviour of line cores post-shock points to a drop in the ionization temperature, although the gas temperature in the model remains high. Shock compression leads to phase-dependent strengthening of Stark-broadened line wings, with the far wings responding first. With velocity-, temperature-, and pressure-sensitive diagnostics, detailed tomography of the pulsation-driven shock in V652 Her seems possible. Even when no shock is present, the dynamical spectrum is significantly different from a model in hydrostatic equilibrium. Using the quasi-static approximation (e.g. at maximum radius) may lead to a considerable underestimate of the star’s mean effective temperature and surface gravity.