Mixing, Metallicity, and Binaries on the Blue Horizontal Branch

蓝色水平分支上的混合、金属丰度和双星在恒星演化的后期会发生许多变化。通过这个奖项，PI试图揭示深层内部混合、质量损失、质量交换和扩散对蓝色水平分支星大气丰度的影响。人们早就知道，在球状星团中，蓝色的水平分支可以呈现出非常不同的外观，乍一看，球状星团的化学成分似乎非常相似。在接下来的工作中，最重要的重点将是研究深层氦混合的作用及其原因。迄今为止的研究表明，它确实发生在两种情况下，在NGC6752蓝色水平分支恒星中，温度足够低，其大气不会受到扩散的影响；在单个扩展的水平分支恒星中，C，N，O丰度与巨星中的相关方式相同，因此预计是深度混合的结果。然而，为了加强这种情况，蓝色恒星覆盖的温度范围要大得多。

"Mixing, Metallicity, and Binaries on the Blue Horizontal Branch"AST-0098725Many changes happen to a star in the late stages of its evolution. With this award, the PI seeks to unravel the effects of deep interior mixing, mass loss, mass exchange and diffusion on the atmospheric abundances of blue horizontal branch stars. It has long been known that the blue horizontal branch can take on a very different appearance in globular clusters which seem at first sight to be very similar chemically. Strongest emphasis in the forthcoming work will be given to investigating the role of deep helium mixing and its causes. Work to date shows evidence that it does occur in two cases, in NGC6752 blue horizontal branch star which are cool enough for their atmospheres not to be influenced by diffusion, and in single extended horizontal branch stars which show C,N,O abundances that are correlated in the same way as in giant stars and are thus expected to have resulted from deep mixing. However, to reinforce this case, blue stars covering a much larger range of temperature are to be observed.