Mapping the Instabilities of Massive Stars

恒星的光度与温度的关系图，即赫茨斯普龙格-罗素(HR)图，在我们对恒星的理解中被证明是非常有价值的。恒星的年龄和质量决定了它在这张图上的位置。在恒星生命的特定时期，它可能会脉动-实际上变得越来越大-因为向外的气体压力和向内的重力并不完全平衡。该项目旨在研究脉动的热、大质量恒星内部的过程。研究人员将使用理论和数值模拟在HR图上创建一张“地图”，描述每种温度和光度组合下恒星内部可能发生的事情。除了在参考文献中公布结果外，还将通过门户网站向公众公布结果。一位已经学习进展顺利的女研究生将用这笔资金完成她的博士论文。一旦恒星经过人力资源图的主序列，它们就会经历许多脉动。造父变星是最广为人知和理解的变星；它们位于HR图中被称为不稳定带的区域。研究人员描述了许多其他不稳定带，并提出了比经典造父变星质量更大的恒星中不稳定的其他原因的理由。例如，除了造父变星的径向对称脉动外，还考虑了脉动-旋转相互作用和非绝热脉动。这项工作将涉及对国际和平研究所开发的MESA和GIRE计算机代码进行修改。

A plot of luminosity versus temperature for stars, known as the Hertzsprung-Russell (HR) diagram, has proven invaluable in our understanding of the stars. A star's age and its mass determine its position on such a diagram. At specific periods during a star's life, it may pulsate---actually get larger and smaller---as gas pressure outward and gravity inward are not quite in balance. This project aims to investigate the processes inside pulsating hot, massive stars. The investigator will use theory and numerical modeling to create a "map" on the HR diagram describing what might be going on inside stars for each combination of temperature and luminosity. The results will be made available to the public via a web portal, in addition to publication of results in the refereed literature. A female graduate student, already well along in her studies, will complete her PhD thesis with this funding.Once stars evolve past the main sequence of the HR diagram, they can undergo many episodes of pulsation. Cepheid variables are the best known and understood; they populate an area of the HR diagram known as the instability strip. The investigator describes many other instability strips and makes the case for other causes of instability in stars more massive than the classical Cepheids. For example, in addition to the radially symmetric pulsations of Cepheids, pulsation-rotation interactions and non-adiabatic pulsation are considered. The work will involve modifications to the MESA and GYRE computer codes, which the PI has developed.