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

恒星是如何诞生和消亡的，这是我们可以问的关于宇宙的最基本的问题。多年来，天文学家一直认为，像太阳这样的恒星会在一系列强大的风中脱落外层，从而形成所谓的“行星状星云”，这是一种明亮的发光气体云，可以跨越一光年或更长时间。在这项研究中，研究人员探索了行星状星云是如何形成的，当恒星出生时有一个兄弟姐妹。天空中超过一半的恒星一生都有一个伴星，这种接近可以改变两颗恒星的进化过程。他们试图了解两颗与太阳质量大致相同的恒星在生命结束时如何相互作用，交换质量并驱动风，从而形成行星状星云。也许只有双星才能形成这样的星云，我们对太阳最终灭亡的看法必须修正。利用强大的超级计算机模拟，他们将追踪两颗轨道恒星的气体流动，并确定这些质量交换如何改变恒星的命运。这些类型的超级计算机算法也用于其他目的，例如高性能计算机行业。该研究项目的重点是通过对行星状星云（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代表了超过一半的物质喷射到ISM的质量和化学演化周期的关键步骤。海王星星云的无处不在和它们的易观测性也使它们成为测试新的天体物理理论的首选实验室。他们将通过准直外流探索双星质量传递和质量损失的动力学。这项研究将阐明在演化的双星系统中吸积盘形成的路径，并试图提供吸积盘上和通过这些吸积盘的吸积速率的限制。利用圆盘中的条件，他们将研究磁塔准直射流的形成和传播。这些波印廷通量主导的流动具有根本性的意义，因为它们代表了一种不同于动能主导的流动的MHD流出，而动能主导的流动已经得到了更多的研究。他们所研究的双星演化（共包络层）、传质和磁流出过程对从Ia型SNe到微类星体等许多天体物理系统的研究具有重要的基础意义。此外，他们开发AstroBEAR AMR代码的工作对计算天体物理学家特别有益，除了他们的研究和AstroBEAR软件的传播所带来的直接科学研究好处之外，PI还是国家公共广播电台13.7宇宙和文化博客的联合创始人，是NPR“All Things Considered”节目的定期科学评论员，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.