Three-dimensional stellar physics simulations of exotic element formation

奇异元素形成的三维恒星物理模拟

• 批准号: RGPIN-2019-07164
• 负责人: Herwig, Falk
• 金额: $ 3.64万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739340
• 关键词: Three; dimensional; stellar; physics; simulations

Advances in observational astronomy have enabled a greatly expanded picture of the different types of abundance patterns and chemical fingerprints that exist in the universe. In large surveys that target metal-poor stars that have formed in the early universe stars with rare and exotic abundance patterns are now frequently found. These abundance observations of stars have evolved into the important tool of galactic archeology to study the formation and evolution of galaxies, and the cosmological processes in the early universe. This project will enhance our understanding of how the elements form in the exotic stellar evolution toward black hole formation of supernova explosion. The first stars that formed shortly after the Big Bang must have possessed yet to be determined unusual modes of element formation as is evident from some of the most intriguing and anomalous abundance patterns found in the most metal-poor and oldest stars. Our approach is based on a new generation of three-dimensional simulations of the turbulent, hydrodynamic conditions of element formation. These simulations require the impressive computing power of Compute Canada's new Niagara supercomputer, that we have used earlier this year together with our international team to perform the largest simulations of turbulent core convection in a massive star. With these three-dimensional simulations we expect to be able to overcome the limitations of present-day one-dimensional spherically-symmetric stellar evolution simulations that include turbulent mixing only via a parameterized model. By including the often violent and energetic feedback from nuclear burning into realistic three-dimensional simulations at very high spatial resolution, using about one half of the entire Niagara computer's 60,000 compute cores at a given time during a simulation run, we will generate unique astrophysics simulation data sets of the turbulent conditions of convective shells in massive stars, such as the merger of a C- and O-burning shell. These simulations will provide a view of unprecedented detail on how the elements form in the final stages of a star's life before exploding as a supernova. An important goal of our research will be to improve our understanding of the exotic conditions in the first massive stars that formed after the Big Bang from the initial, pristine and metal-free material. One-dimensional models suggest that during interactions of convective H- and He-burning shells as much energy per unit time as an entire galaxy produces would be generated inside the star, although of course only for a short time. Our three-dimensional simulations will reveal how a real star would respond to such extreme and energetic events. They will show if and how the anomalous abundance patterns observed in the most metal-poor and oldest stars can originate in these first stars. In this way our research will help to solve the puzzle of element formation and evolution in the early universe.

观测天文学的进步极大地扩展了宇宙中存在的不同类型的丰度模式和化学指纹的图景。在针对早期宇宙中形成的贫金属恒星的大型调查中，现在经常发现具有罕见和奇异丰度模式的恒星。这些对恒星的大量观测已发展成为银河考古学的重要工具，用于研究星系的形成和演化以及早期宇宙的宇宙学过程。 该项目将增强我们对奇异恒星演化过程中元素如何形成以及超新星爆炸黑洞形成的理解。大爆炸后不久形成的第一批恒星必定具有尚未确定的不寻常的元素形成模式，这一点从在金属最贫乏和最古老的恒星中发现的一些最有趣和异常的丰度模式中可以明显看出。 我们的方法基于对元素形成的湍流、流体动力学条件的新一代三维模拟。这些模拟需要加拿大计算公司的新型尼亚加拉超级计算机具有令人印象深刻的计算能力，今年早些时候我们与我们的国际团队一起使用该超级计算机对大质量恒星中的湍流核心对流进行了最大的模拟。 通过这些三维模拟，我们期望能够克服当今一维球对称恒星演化模拟的局限性，该模拟仅通过参数化模型进行湍流混合。通过将核燃烧产生的经常剧烈和高能的反馈纳入具有非常高空间分辨率的真实三维模拟中，在模拟运行期间的给定时间使用整个 Niagara 计算机 60,000 个计算核心的大约一半，我们将生成独特的天体物理模拟大质量恒星对流壳层湍流条件的数据集，例如碳燃烧壳层和氧燃烧壳层的合并。这些模拟将提供前所未有的细节，了解恒星生命最后阶段在爆炸为超新星之前元素如何形成。 我们研究的一个重要目标是提高我们对大爆炸后由最初的、原始的、不含金属的材料形成的第一批大质量恒星的奇异条件的理解。一维模型表明，在对流氢燃烧壳层和氦燃烧壳层相互作用期间，恒星内部每单位时间会产生相当于整个星系产生的能量，尽管当然只是很短的时间。我们的三维模拟将揭示真正的恒星将如何应对这种极端和充满活力的事件。他们将展示在金属最贫乏和最古老的恒星中观察到的异常丰度模式是否以及如何起源于这些第一代恒星。这样我们的研究将有助于解决早期宇宙的元素形成和演化之谜。