From Core to Outflow: The Dynamics of Binary Interactions and the Generation of Collimated Flows in Evolved Stars

恒星是如何诞生的，它们又是如何消亡的，这代表了我们可以对宇宙提出的最基本的问题。多年来，天文学家们一直认为，像我们的太阳这样的恒星会在一系列强风的作用下脱离外层，从而结束生命，形成所谓的行星星云，这是一种明亮发光的气体云，跨度可达一光年或更长时间。在这项研究中，研究人员探索了当恒星出生时有兄弟姐妹时，行星状星云是如何形成的。天空中超过一半的恒星都与伴侣共度一生，这种亲密关系可以改变这两颗恒星的进化进程。他们试图了解两颗质量与太阳大致相同的恒星如何在生命的末期相互作用，交换质量并驱动风，从而形成行星状星云。可能只有双星才会形成这样的星云，我们关于太阳最终灭亡的想法必须修正。使用强大的超级计算机模拟，他们将跟踪来自这两颗轨道恒星的气体流动，并确定这些质量交换如何改变这两颗恒星的命运。这些类型的超级计算机算法还用于其他目的，例如高性能计算机工业。这一研究项目的重点是通过对行星星云(PNE)的具体新研究来了解演化双星中的磁化外流。作为这些恒星质量损失的最后阶段，PNE代表着抛射到ISM中的一半以上物质的质量和化学演化周期中的关键一步。PNE的无处不在和易于观察，也使它们成为测试新天体物理理论的首选实验室。他们将探索双星通过平行流出的质量转移和质量损失的动力学。这项研究将阐明在进化的双星系统中吸积盘形成的途径，并试图对这些盘上和通过这些盘的吸积率提供限制。利用圆盘中的条件，他们将研究磁塔准直外流的形成和传播。这些以Poynting-Flux为主的流动具有基本意义，因为它们代表了不同类型的MHD外流，而不是已得到更多研究的动能主导流。它们研究的双星演化(公共包络)、质量传递和磁流出过程对于研究从IaSNE到微类星体的许多天体物理系统具有重要的基础意义。此外，他们开发AstroBEAR AMR代码的工作除了从他们的研究和AstroBEAR软件的传播中获得直接的科学研究好处之外，还对计算天体物理学家有特别的好处。PI是国家公共广播13.7宇宙和文化博客的联合创始人，该博客是NPR的All Things Consired的定期广播科学评论员，也是《纽约时报》的定期撰稿人。在这个项目中，他们将为电台开发一系列广播节目，跟踪学生和博士后在进行研究项目时的进展。

How stars are born and how they die represent the most fundamental kinds of questions we can ask about the Universe. For many years astronomers believed a star like our own sun would end its life by shedding it outer layers in a series of powerful winds leading to the formation of what is called a 'planetary nebula', a brightly glowing gas cloud that can span a light year or more. In this study the investigators explore how planetary nebula can form when stars are born with a sibling. More than half the stars in the sky live their entire life with a companion and that proximity can change the course of evolution for both stars. They seek to understand how two stars with about the same mass as the sun can interact at the end of their lives exchanging mass and driving winds that will create a planetary nebula. It may be that only binary stars form such nebula and our ideas of the Sun's eventual demise must be revised. Using powerful supercomputer simulations they will track the gas flows from the two orbiting stars and determine how these mass exchanges can alter the fate of the stars. These kinds of supercomputer algorithms are also used for other purposes, such as the high performance computer industry. This research project is focused on understanding magnetized outflows in evolved binary stars through specific new studies of Planetary Nebulae (PNe). As the final stage of mass loss for these stars, PNe represent a critical step in the mass and chemical evolution cycle for more than half the material ejected into the ISM. The ubiquity of PNe and their ease of observation also make them premier laboratories for testing new astrophysical theories. They will explore the dynamics of binary star mass transfer and mass loss through collimated outflows. The research will explicate routes through which accretion disks can form in evolved binary systems and attempt to provide limits on the accretion rates onto and through those disks. Using the conditions in the disks they will then study the formation and propagation of magnetic tower collimated outflows. These Poynting-Flux Dominated flows are of fundamental interest because they represent a different category of MHD outflow from the kinetic energy dominated flows that have received greater study. The binary evolution (Common Envelope), mass transfer and magnetic outflow processes they study are of fundamental importance to the study of many astrophysical systems from Type Ia SNe to Microquasars. In addition their work developing the AstroBEAR AMR code is of particular benefit computational astrophysicists Beyond the direct scientific research benefits of their study and the dissemination of the AstroBEAR software, the PI is a co-founder of National Pubic Radio's 13.7 Cosmos and Culture Blog, a regular on-air science commentator for NPR's All Things Considered and regular contributor to the New York Times. In this project they will develop a series of on-air programs for radio that will track the progress of a student and the post-doc as they carry out the research project.