Nonlinear Stellar Pulsations

很可能所有的恒星都是脉动的，尽管大多数恒星的脉动很小，而且恒星距离很远，很难检测到脉动。例如，在太阳的情况下，最近才用新开发的仪器探测到脉动，这就产生了“日震学”这门科学。然而，有一些恒星的脉动相当强烈。这些恒星明显地变得更亮、更暗，它们会膨胀和收缩。有些恒星具有相当规律的周期，例如天琴座和天琴座RR恒星；另一些恒星的脉动相当不稳定，例如金牛座RV恒星。首席研究员(PI)建议继续他目前由NSF资助的对所有类型的脉动星的理论和数值研究，从Cepeheids和RR Lyra星到半正则星和RV Tauri星。计算方法将由“半解析振幅方程形式和数值流体力学的明智混合”组成。目标将是开发单参数脉动恒星模型族，而不是研究特定的观测恒星。为了支持这项研究，PI建议扩展他目前的计算机代码，使其更现实，并根据混沌理论解释恒星脉动。

Quite possibly all stars pulsate, though in most stars the pulsations are so small and the stars are so distant that the pulsations are very difficult to detect. For example, in the case of the sun, pulsations have been detected only recently with newly developed instrumentation, giving rise to the science of "helioseismology." Ther are, however, stars that pulsate rather strongly. These stars grow visibly brighter and dimmer, and they expand and contract. Some do so with rather regular periods, as for example the Cepeheid and RR Lyra stars; others are quite erratic in their pulsations, such as the RV Tauri stars. The Principal Investigator (PI) proposes to continue with his current NSF funded theoretical and numerical study of pulsating stars of all types, from Cepeheids and RR Lyra stars to Semi- Regulars and the RV Tauri stars. The computing method will consist of a "judicious mixture of semi-analytical amplitude equation formalism and of numerical hydrodynamics." The goal will be to develop one-parameter families of pulsating star models, rather than to study specific observed stars. In support of this study, the PI proposes to expand his current computer codes to make them more realistic and to interpret stellar pulsation in terms of chaos theory.