Investigations of the Common-Envelope Phase of Binary Star Evolution

各种各样令人兴奋的天体物理现象都涉及到一对相互绕转的恒星，它们经常交换或共享物质，有时合并形成一个单一的物体。无论它们的初始或最终状态如何，这些系统都会经历一个阶段，在这个阶段中，两个物体都在同一个“公共包络”内运行，通过这个包络，它们交换和共享物质。对这一现象进行复杂的计算机模拟，可能是解释决定这一系统最终命运的所有因素的唯一方法。PI和他的合作者将进行这样的模拟，这是由于太级和千万亿级计算技术的发展和国家科学基金会对高性能计算基础设施的投资而成为可能的。他们将使用作为该项目的一部分开发的软件，通过为在线数字演示室网站和计算天体物理学的新课程创建交互式双星模拟模块来加强本科天文学教育。学生将参与研究和开发教育材料。该团队将进行计算机模拟来研究共同包层的物理特性，这是一个短暂但至关重要的阶段，可能会导致各种各样的天体物理现象，包括某些类型的超新星、伽马射线爆发、恒星或黑洞之间的合并。这个阶段本质上是三维的，不能用一维模拟来研究，而一维模拟是我们理解单星演化的基础。他们将专注于了解共同包层双星在喷出较大恒星的外层大气时所能利用的能量来源，以及预测两颗恒星合并时的相位。

A wide variety of exciting astrophysical phenomena involve a pair of stars orbiting each other, often exchanging or sharing material and sometimes merging to form a single object. Regardless of their initial or final state, these systems pass through a phase in which both objects orbit within the same "common envelope", through which they exchange and share material. Complex computer simulations of this phenomenon are perhaps the only way to account for all of the factors that determine the ultimate fate of such a system. The PI and his collaborators will carry out such simulations, which are made possible by the development of terascale and petascale computing technology and investments by NSF in high-performance computing infrastructure. They will use software developed as part of this project to enhance undergraduate astronomy education by creating interactive binary star simulation modules for an online Digital Demo Room site and for a new course in computational astrophysics. Students will be involved both in the research and in developing education materials.The team will carry out computer simulations to study the physics of common envelopes, a short-lived but crucial phase in the life of close binary stars that may lead to a wide variety of astrophysical phenomena, including certain types of supernovae, gamma-ray bursts, and mergers between stars or black holes. This phase is inherently three-dimensional and cannot be studied using the one-dimensional simulations that underlie our understanding of single-star evolution. They will focus on understanding the sources of energy a common-envelope binary can draw upon in ejecting the outer atmosphere of the larger star and on predicting the appearance of the phase in cases in which the two stars merge together.