Magnetic fields and stellar evolution

磁场和恒星演化

• 批准号: RGPIN-2016-06383
• 负责人: Wade, Gregg
• 金额: $ 4.37万
• 依托单位: Royal Military College of Canada
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=667923
• 关键词: Magnetic; fields; stellar; evolution

All stars are natural magnets, thanks to the dynamic, electrically conductive gases that compose them. And because the magnetic fields of stars can be very strong, they represent a basic element in astrophysicists' theory of stellar structure and evolution. In recently years it has been clearly demonstrated that magnetic fields have essential impacts on stellar lives, modifying their interior flows of gas, changing their internal rotational profiles and distributions of nucleosynthetic chemicals, channeling and modifying their outflowing winds, and slowing their surface rotation through so-called "magnetic braking". Ultimately, these effects result in important changes in the evolution of stars, leading in particular to modifications of the relationships between stellar temperatures, luminosities, sizes and ages. They also influence the important outputs of stars in terms of the mass and luminous energy injected into the surrounding interstellar medium during their lives. More remarkably, they can also influence the dramatic supernova explosions that mark the deaths of the most massive stars. These effects directly impact the properties of exotic remnant white dwarf and neutron stars, and change how populations of stars contribute to the structure and chemistry of their local Galactic environments. *** As stars age and evolve, so too do their magnetic fields. Hence we expect to observe important transformations of stellar magnetic fields as stars pass through various stages of nuclear burning and undergo large changes to their temperatures, luminosities and sizes. As a consequence, the magnetic field of a star at one stage of its life may appear very different from that at a later stage. It is therefore of great interest to understand the relationships between magnetic fields observed in stars at very different evolutionary stages. For example, can the magnetic fields from an earlier evolutionary stage "seed" the production of a very different magnetic field at a later stage? Do magnetic fields with similar characteristics in stars at very different evolutionary stages have any direct relationship? ***With my research team of Canadian and international students and scientists, I am working to answer many of the questions prompted by the issues described above. The principal aim of the research described in this proposal is to continue my group's systematic exploration of the characteristics of magnetic fields of stars of all types, using telescopes around the globe and in space. My proposal has two main goals: to quantitatively understand how magnetic fields influence stellar structure and evolution, and to understand how the observable magnetic fields of stars transform over stellar evolutionary timescales. *** **

所有的恒星都是天然的磁铁，这要归功于构成它们的动态、导电气体。由于恒星的磁场可能非常强，它们代表了天体物理学家恒星结构和演化理论的一个基本元素。近年来，已经清楚地表明，磁场对恒星生命有重要的影响，改变它们内部的气体流动，改变它们内部的旋转轮廓和核合成化学物质的分布，引导和改变它们的流出风，并通过所谓的“磁制动”减缓它们的表面旋转。最终，这些影响导致了恒星演化的重要变化，特别是导致了恒星温度、光度、大小和年龄之间关系的改变。它们还影响恒星在其生命期间向周围星际介质注入的质量和光能的重要输出。更值得注意的是，它们还可以影响戏剧性的超新星爆炸，这标志着最大质量恒星的死亡。这些影响直接影响了外来残余白矮星和中子星的性质，并改变了恒星种群对其本地银河系环境的结构和化学的贡献。随着恒星年龄的增长和演化，它们的磁场也在变化。因此，当恒星经过核燃烧的各个阶段，并经历温度、光度和大小的巨大变化时，我们期望观察到恒星磁场的重要变化。因此，一颗恒星在其生命的某一阶段的磁场可能会与后来阶段的磁场大不相同。因此，了解在不同演化阶段的恒星中观测到的磁场之间的关系是非常有趣的。例如，早期进化阶段产生的磁场能否“播下”在后期产生非常不同的磁场的种子？处于不同演化阶段的恒星中具有相似特征的磁场是否有直接关系？***与我的加拿大和国际学生和科学家组成的研究团队，我正在努力回答上述问题所引发的许多问题。这项研究的主要目的是利用全球和太空中的望远镜，继续我的小组对所有类型恒星磁场特征的系统探索。我的提议有两个主要目标：定量地了解磁场如何影响恒星的结构和演化，以及了解恒星的可观测磁场如何在恒星演化的时间尺度上发生变化。* * * * *