Gravitationally Driven Instabilities in the Early & Late Stages of Stellar Evolution

旋转的恒星容易受到各种全球性的引力驱动的不稳定性的影响，特别是在最早的时期（例如，原恒星）和最新的（例如，当它们最有可能快速旋转时，它们的演化阶段。这些包括，例如，广泛的非径向脉动。双星系统中的恒星通过相互间的引力相互作用可能会遇到更多的不稳定性，特别是潮汐和质量传递不稳定性。这些不稳定性中的任何一种都可能导致星星的全球结构发生重大变化，并改变星星的演化。 在致密物体的情况下，如中子星，它们可能会产生可测量的引力辐射水平。 此外，在我们能够真实地模拟快速旋转的原恒星和原恒星气体云中各种引力驱动的不稳定性之前，我们不太可能理解双星的起源。该项目的主要研究者正在扩展他对旋转恒星中引力驱动的不稳定性的详细研究，使用全三维非线性流体动力学技术来确定在什么条件下出现某些关键的不稳定性，以及这些不稳定性的非线性发展在天体物理学上的重要意义。更广泛的影响。为了进一步理解天体物理系统中的引力不稳定性，必须开发的高性能计算工具的类型也用于在大气科学，海岸研究，健康科学的某些领域以及工程的许多子领域取得重大研究进展。这位路易斯安那州立大学的研究人员和他的学生定期与应用数学家、计算机科学家以及众多同事交流思想和计算技术，这些同事在研究中采用计算流体动力学工具来模拟飓风风暴潮、人眼中的流体流动、先进燃气涡轮机系统中的冷却流、海岸侵蚀以及石化搅拌罐中的反应流。这些研究领域中的大多数直接影响路易斯安那州的环境和经济福祉。主要调查员将继续参与K-12和一般公众外联项目，特别是与当地高地路公园观测站和巴吞鲁日的一所中学有关的项目，在这些项目中，正在作出重大努力，加强年轻妇女在科学和数学方面的早期培训。

Rotating stars are susceptible to a variety of global, gravitationally driven instabilities, especially during the earliest (e.g., protostellar) and latest (e.g., compact object) phases of their evolution when they are most likely to be rotating rapidly. These include, for example, a wide spectrum of nonradial pulsations. An even larger number of instabilities may be encountered by stars in binary systems through their mutual gravitational interaction, in particular, tidal and mass transferring instabilities. Any one of these instabilities may result in substantial alterations in the star's global structure and change the star's evolution. In the case of compact objects, such as neutron stars, they may give rise to measurable levels of gravitational radiation. Also, we're not likely to understand the origin of binary stars until we are able to realistically model the variety of gravitationally driven instabilities in rapidly rotating protostars and protostellar gas clouds. The Principle Investigator of this project is extending his detailed investigations of gravitationally driven instabilities in rotating stars, using fully three-dimensional, nonlinear hydrodynamical techniques to determine under what conditions certain key instabilities arise, and what the astrophysically important implications are of the nonlinear development of these instabilities. Broader Impacts. The types of high-performance computational tools that must be developed in order to further our understanding of gravitational instabilities in astrophysical systems are also used to make significant research advancements in atmospheric sciences, coastal studies, certain areas of the health sciences, and numerous subfields of engineering. This Louisiana State University researcher and his students regularly exchange ideas and computational techniques with applied mathematicians, computer scientists, and numerous colleagues who employ computational fluid dynamics tools in their research to model hurricane storm surges, fluid flow in the human eye, cooling flows in advanced gas turbine systems, coastal erosion, and reacting flows in petrochemical stirring tanks. Most of these areas of research directly influence Louisiana's environmental and economic well-being. The Principle Investigator will continue to be involved in K-12 and general public outreach projects, especially those associated with the local Highland Road Park Observatory and one secondary school in Baton Rouge where substantial efforts are being made to strengthen the early training of young women in science and mathematics.