Studies in Common Envelope Evolution

在没有显著的角动量和质量损失的情况下，很难在进化情景中再现许多类近距离双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的转移到一个共同的包络层，这个包络层随后由于两个组成部分之间的引力相互作用而被抛出。这个项目将对大质量恒星（如适用于包含中子星和黑洞的低质量x射线双星）以及低到中等质量恒星（如适用于包含白矮星的灾难性变量）的常见包络演化阶段进行研究。研究的主要目标是确定长轨道周期的祖双星系统转换并作为短周期系统生存的参数，以及发生合并的参数。这些研究包括对多维流体动力学过程的处理，在本提案中，研究人员将使用自适应并行模拟代码对共同包络阶段进行高分辨率三维研究。这项研究为理解包含致密天体的紧密双星系统的形成和演化提供了基础

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.***