The physical nature of be stars and their circumstellar disks

恒星及其星周盘的物理性质

• 批准号: 227239-2011
• 负责人: Sigut, Thomas
• 金额: $ 2.04万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=546726
• 关键词: physical; nature; stars; their; circumstellar

Rotation, or "spin," is ubiquitous in the Universe. The Earth, the Sun, and the Milky Way Galaxy all rotate. All of these objects formed from gravitational collapse after the Big Bang, and this collapse acts naturally to increase any initial small, random rotation. An intriguing question is how this rotation shapes the lives of stars, planets, and galaxies. Astronomers know that rapid rotation can be a key element in the evolution of stars more massive than about three times the mass of the Sun. While such stars are rarer than solar-mass stars, they supply most of energy and mass to the interstellar medium of the Milky Way (out of which new stars form), and they synthesize (through nuclear burning and supernova explosions) all of the chemical elements essential for life. However a coherent understanding of the role rotation plays in the lives of massive stars is far from complete. My research will address this problem by focusing on the most rapidly rotating, core hydrogen burning stars, the B emission-line or Be stars. Be stars rotate with periods of about one day (compared to about one month for our Sun), and they are known to possess a disk of gas surrounding their equator. However, rotation rates for Be stars are highly uncertain, and the role that rapid rotation plays in forming their disks is unknown. I will use new computational techniques, along with new observations, some obtained at the Canada-France-Hawaii Telescope, to accurately estimate how fast Be stars rotate. Any model of how their disks form will have to be consistent with these rotation rates. I will also attempt to detect patterns in the abundances of the elements in the atmospheres of these stars to find the first evidence for internal mixing in Be stars driven by their rapid rotation. This will place important new constraints on the rotational evolution of massive stars and will potentially help to understand exotic events in the universe, such as gamma-ray bursts which are though to form from the supernova explosions of the most massive, rapidly rotating stars. Canada as a whole will benefit from this research through the graduate students trained in high-performance computation and data visualization required to complete these research projects.

旋转或“自旋”在宇宙中无处不在。地球、太阳和银河系都在旋转。所有这些物体都是由大爆炸后的引力塌缩形成的，这种塌缩会自然地增加任何最初的小而随机的旋转。一个有趣的问题是这种旋转如何塑造恒星、行星和星系的生命。天文学家知道，快速旋转可能是质量超过太阳质量三倍的恒星演化的关键因素。虽然此类恒星比太阳质量的恒星更为罕见，但它们为银河系的星际介质（新恒星形成）提供了大部分能量和质量，并且它们合成（通过核燃烧和超新星爆炸）所有化学物质生命必需的元素。然而，对自转在大质量恒星生命中所扮演的角色的连贯理解还远未完成。我的研究将通过关注旋转速度最快的核心氢燃烧恒星、B 发射线或 Be 恒星来解决这个问题。 Be恒星的旋转周期约为一天（而太阳的旋转周期约为一个月），并且已知它们在赤道周围拥有一个气体盘。然而，Be 星的自转速率高度不确定，并且快速自转在形成其盘中所起的作用尚不清楚。我将使用新的计算技术以及新的观测结果（其中一些是在加拿大-法国-夏威夷望远镜获得的）来准确估计 Be 恒星的旋转速度。任何关于它们的圆盘如何形成的模型都必须与这些旋转速率一致。我还将尝试检测这些恒星大气中元素丰度的模式，以找到 Be 恒星快速旋转驱动下内部混合的第一个证据。这将为大质量恒星的旋转演化设置重要的新限制，并有可能有助于理解宇宙中的奇异事件，例如伽马射线爆发，这种爆发被认为是由最大质量、快速旋转恒星的超新星爆炸形成的。整个加拿大将通过接受完成这些研究项目所需的高性能计算和数据可视化培训的研究生从这项研究中受益。