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

从核心到流出：双星相互作用的动力学和演化恒星中准直流的生成

• 批准号: 1515648
• 负责人: Adam Frank
• 金额: $ 38.8万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1515648&HistoricalAwards=false
• 关键词: Core; Outflow; Dynamics; Binary; Interactions

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.

恒星是如何诞生和死亡的，这是我们可以问的关于宇宙的最基本的问题。 多年来，天文学家们一直认为，像我们的太阳这样的星星会在一系列强风中脱落外层，从而形成所谓的“行星状星云”，这是一种明亮发光的气体云，跨度可达一光年或更长。 在这项研究中，研究人员探索了行星状星云如何在恒星诞生时形成兄弟姐妹。 天空中超过一半的恒星一生都有一个伴星，这种接近可能会改变这两颗恒星的进化过程。 他们试图了解两颗质量与太阳相当的恒星在生命的最后如何相互作用，交换质量和驱动风，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中的质量和化学演化周期的关键步骤。 PNe的普遍存在和易于观察也使它们成为测试新天体物理理论的首要实验室。他们将探索通过准直流出的双星星星质量转移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形成吸积盘的途径，并试图限制吸积盘上和通过吸积盘的吸积速率。 利用磁盘中的条件，他们将研究磁塔准直流出的形成和传播。 这些坡印廷通量主导的流动是根本的利益，因为他们代表了不同类别的MHD流出的动能主导的流动，已收到更多的研究。他们研究的双星演化（共包络）、质量转移和磁外流过程对从Ia型超新星到微类星体的许多天体物理系统的研究具有重要意义。此外，他们开发AstroBEAR AMR代码的工作特别有利于计算天体物理学家 除了他们的研究和AstroBEAR软件的传播的直接科学研究的好处，PI是国家公共广播电台的13.7宇宙和文化博客的联合创始人，NPR的所有事情都考虑到了定期的空中科学评论员和纽约时报的定期撰稿人。 在这个项目中，他们将开发一系列的广播节目，将跟踪学生和博士后的进展，因为他们进行的研究项目。