Studies in Common Envelope Evolution

AST-0200876 PI Taam在没有显著的角动量和质量损失的情况下，很难在进化的场景中重现许多类近距离双星星星系统的观测质量和轨道周期。促进这些损失的机制涉及轨道角动量和能量转移到一个共同的包层，随后由于两个组件之间的引力相互作用而被弹出。本项目将研究大质量恒星（适用于包含中子星和黑洞的低质量X射线双星）以及低至中等质量恒星（适用于包含白色矮星的激变变星）的这种共同的演化包络阶段。研究的主要目标将是确定长轨道周期的祖先双星系统转变为短周期系统并存活下来的参数，以及合并发生的参数。这些调查包括多维流体动力学过程的治疗，并在本提案中，调查人员将进行高分辨率的三维研究的共同信封阶段使用自适应，并行模拟代码。这项研究提供了一个基础，在此基础上可以理解包含紧凑物体的近距离双星系统的形成和演化。

AST-0200876PI TaamThe observed masses and orbital periods for many classes of close binary star systems are difficult to reproduce in evolutionary scenarios without significant angular momentum and mass loss. A mechanism which facilitates these losses involves the transfer of orbital angular momentum and energy to a common envelope which is subsequently ejected as a result of the gravitational interactions between the two components. This common envelope phase of evolution will be investigated in this project for massive stars (as applied to low mass X-ray binaries containing neutron stars and black holes)as well as low to intermediate mass stars (as applied to cataclysmic variables containing white dwarf stars). The primary goal of the research will be to determine the parameters for which the progenitor binary systems at long orbital periods are transformed and survive as short period systems, and the parameters for which mergers takes place. These investigations include the treatment of multi-dimensional hydrodynamical processes, and in this proposal the investigators will undertake high resolution three dimensional studies of the common envelope phase using an adaptive, parallel simulation code. This research provides a foundation upon which the formation and evolution of close binary systems containing compact objects can be understood.***