Nonlinear Stellar Pulsations

对变星的研究是天文学的基础。变异性的特性提供了比静态恒星更多的信息，它们对我们对恒星结构和演化、星系演化和宇宙学的理解有很大的贡献。这个项目涉及恒星不稳定性的建模和对其系统的理解。提出了一种新的非线性自适应水动力代码，使模型与观测值之间的一致性更好。这种新方法解决和跟踪脉动周期中的重要物理特征。在这项研究中，新代码的结果将与PI先前开发的脉动半解析理论相结合，以深入了解机制。将考虑的恒星范围从规则变化的造父变星和天蝎座RR星到不稳定的金牛座RV星和半规则变星。随机噪声对脉动的影响以及时变信号的分析方法也将在理论结果与观测结果比较的背景下进行研究。

The study of variable stars is basic to much of astronomy. The properties of the variability provide more information than can be obtained from static stars and they contribute greatly to our understanding of stellar structure and evolution, galactic evolution and cosmology. This project concerns modelling of stellar instability and understanding its systematics. A new nonlinear adaptive hydrodynamic code which produces better agreement between the models and the observations has been developed. This new method resolves and tracks the important physical features during the pulsation cycle. In this study, the results from the new code will be combined with the PI's previously developed semi-analytical theory of pulsation to gain insights into the mechanisms. The stars which will be considered range from the regularly varying Cepheids and RR Lyrae stars to the erratic RV Tauri stars and Semi-regular variables. The effects of stochastic noise on pulsations and methods of analysis of time-dependent signals will also be studied in the context of comparing the theoretical results with observation.