Hydrodynamic Pulsation Modes of Multi-frequency Radiative Transfer for Mass-losing Early Type Stars

研究了具有改进的辐射传递的水动力脉动模型。在本研究中，我们集中对辐射传递进行了线性分析和非线性模拟建模的统一处理。作为本研究的第一步，我们采用非扩散近似代替平衡扩散近似作为辐射传递的近似。我们已经有了平息的结果。我们构建了用于线性分析和非线性模拟的计算机代码。我们可以扩展可变爱丁顿因子近似的代码，以更好地处理辐射传递。我们将目前的代码应用于后AGB恒星，作为质量较小的超巨星和经典造父变星的一个例子。对于线性分析，我们比较了模型的脉冲周期和增长率。非平衡近似对这两个量产生很小的变化。对于非线性模拟，我们比较了模型光球处可观测量的时间变化。新的近似值在这些值上产生非常小的变化。我们有一个关于后AGB恒星不规则脉动的有趣结果。众所周知，后AGB恒星的脉动模型表现为不规则脉动固定发光的超巨星。在模型参数相同的情况下，新模型与传统扩散近似模型得到的不规则脉动的时间演化有很大的不同。我们怀疑，这种差异来自于混沌的特征。在混沌系统中，基本方程的微小变化可能会在以后的时间内产生巨大的时间演化差异，即使计算是从相同的初始条件开始的，也就是行为的情况。

Hydrodynamic Pulsation models with an improved radiative transfer is studied. In this study, we concentrated in unified treatment of radiative transfer for linear analysis and non-linear simulation modeling.. As the first step of this study, we took non-diffusion approximation as the approximation of radiative transfer instead of equilibrium diffusion approximation. We have the fallowing results.1. We constructed computer codes for both linear analysis and non-linear simulation. We may extend the codes for the variable Eddington factor approximation for more improved treatment of radiative transfer. We applied the present codes to post-AGB stars as am example of less-massive supergiants stars as well as classical Cephieds.2. For linear analysis we compare the pulsation periods and the growth rate of models. The non- equilibrium approximation yields very small change for both the quantities. For non-linear simulation, we compared the time variations of observable quantities at the photosphere of models. The new approximation yields very small changes on these values.3. We have an interesting result on irregular pulsation of the post-AGB stars. It is known that pulsation model for post-AGB stars shows irregular pulsation fix luminous supergiant stars. The new model yields quite large different time evolution of irregular pulsation compared with ones which is obtained with the model of traditional diffusion approximation for the same values of model parameters. We suspect that the difference comes form the characteristics of chaos. In chaos system, a small change of basic equations may yield great differences of time evolution at later time, even if the calculation starts with the same initial conditions for the same model That is the case of the behavior.