Interacting Binaries: Mass Transfer and Common Envelope Evolution

夜空中超过一半的星星都有兄弟姐妹。 它们不是单独通过出生、中年和死亡而成熟，而是与一个或多个伴星一起生活。 “双星”，即两颗恒星在它们的生命周期中一起发展，是多星星系统中最常见的形式。 研究人员试图了解双星星星生命周期的最后阶段，在这个阶段，较小的星星坠入较大恒星的大气层，导致称为共同包络演化（CEE）的壮观现象。 CEE阶段是双星星星生命周期中最难理解也是最重要的阶段之一。 这很重要，因为宇宙中有许多？最奇怪、最奇特的现象来自普通信封阶段。 最近最著名的CEE事件的例子是黑洞-黑洞合并，在NSF资助的LIGO项目通过引力波观察到后，它成为世界各地的头条新闻。建模CEE需要最复杂的超级计算机模拟，因为这个过程是如此激烈，发生得如此之快。 研究人员将使用新开发的超级计算机代码来揭示CEE的新细节，并解决长期存在的关于双星如何快速缩小轨道并将大量物质送入太空的谜团。 他们的工作将通过他们的代码产生“合成观测”的能力与观测密切相关，这些观测可以直接与天空中看到的进行比较。 此外，研究人员将通过为流行杂志和在线杂志撰写的文章将这项研究介绍给公众。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

More than half of the stars in the night sky come with siblings. Instead of maturing through their birth, middle age and death alone, they live their lives with one or more companion stars. "Binary stars", where two stars progress through their life cycle together, are the most common form of multiple star systems. The investigators seek to understand the final stages of the binary star life cycle, where the smaller star plunges into the atmosphere of the larger one leading to the spectacular phenomena called Common Envelope Evolution (CEE). The CEE stage is one of the most difficult to understand and one of the most important stages of the binary star life cycle. It is important because many of the Universe?s strangest and most exotic phenomena come from the Common Envelope stage. The most famous recent example of a CEE event was the Black Hole-Black Hole merger, which made headlines across the world after being observed via gravitational waves with the NSF funded LIGO project.Modeling CEE requires the most sophisticated supercomputer simulations because the process is so violent and occurs so quickly. The investigators will use a newly developed supercomputer code to reveal new details of CEE and resolve long-standing mysteries about how the binary stars quickly shrink their orbit and drive huge amounts of material into space. Their work will be closely tied to observations via their codes' ability to produce "synthetic observations" that can be directly compared with what is seen on the sky. In addition, the investigators will bring this research to the public through articles written for popular and on-line magazines.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.