Pulsation evolution and hydrodynamics of rapidly rotating stars

快速旋转恒星的脉动演化和流体动力学

• 批准号: 288252-2007
• 负责人: Deupree, Robert
• 金额: $ 2.01万
• 依托单位: Saint Mary's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=363745
• 关键词: Pulsation; evolution; hydrodynamics; rapidly; rotating

Our knowledge of the structure and evolution of stars has increased greatly with the advent of high powered digital computers. We have understood the basic life cycle for stars for about four decades now, but our failure to match increasingly refined observations demonstrates that we do not understand everything. For example, the traditional models predict neither the enhancement of the surface abundances of some elements which must be created deep inside the star and transported to the surface nor the correct values for all the observed oscillation periods of stars appreciably more massive than the sun.Rotation, not included in the traditional models,  has been identified as the possible reason for these discrepancies. This may come not only through the alteration of the stellar structure produced by the rotational force, but also through short and intermediate time scale motion produced by instabilities that rotation can cause. The motion produced by these instabilities transports material and angular momentum throughout the star.  The multi-dimensional calculations proposed in this research can be expected to reproduce the stellar structure adequately for a given angular momentum distribution. With some further development, it is expected that the evolution of the composition and angular momentum distributions produced through these rotational instabilities can be followed as well. This should allow us to narrow the possible angular momentum distribution possibilities that stars have. This redistribution of material and angular momentum begins early in the star's life. Later stages of stellar evolution will be affected by this and this may be the key to understanding some discrepancies between observation and models in these later phases as well.The computational methods utilized have application in many other areas of research: climate studies, turbulence research, and defense related work.

随着高性能数字计算机的出现，我们对恒星的结构和演化的了解大大增加了。我们已经了解恒星的基本生命周期大约40年了，但我们未能与日益精细的观测相匹配，这表明我们并不了解一切。例如，传统的模型既不能预测某些元素的表面丰度的增加，这些元素必须在星星内部深处产生并被输送到表面，也不能预测所有观测到的比太阳大得多的恒星的振荡周期的正确值。旋转，没有包括在传统的模型中，被认为是这些差异的可能原因。这可能不仅是因为自转力改变了恒星的结构，也可能是因为自转引起的不稳定性造成的短时间和中等时间尺度的运动。由这些不稳定性产生的运动将物质和角动量输运到整个星星中，对于给定的角动量分布，本研究提出的多维计算方法可望充分再现恒星的结构。随着一些进一步的发展，预计也可以跟踪通过这些旋转不稳定性产生的成分和角动量分布的演变。这应该使我们能够缩小恒星可能的角动量分布的可能性。这种物质和角动量的重新分配在星星生命的早期就开始了。恒星演化的后期阶段将受到这种影响，这可能是理解观测和模型之间的差异的关键，在这些后期阶段，以及所使用的计算方法在许多其他领域的研究：气候研究，湍流研究，和国防相关的工作。