The Final Hour of a Massive Star: Silicon Shell Burning and the Subsequent Supernova

大质量恒星的最后时刻：硅壳燃烧和随后的超新星

• 批准号: 1716134
• 负责人: Eric Lentz
• 金额: $ 23.24万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1716134&HistoricalAwards=false
• 关键词: Final; Hour; Massive; Star; Silicon

The final stage of life for a massive star (larger than about nine times the mass of the Sun) is the nuclear fusion ("burning") of silicon (SiSB) to create iron in a shell around an inert iron core, increasing the mass of the iron core.  This stage can last up to an hour until growth of the iron core triggers its collapse to a compact and dense neutron star (NS) surrounded by accreting material. Subatomic particles called neutrinos emitted by the new NS heat the material and drive it out in a shock front through the surrounding star, generating a supernova explosion that delivers newly made elements into the interstellar medium of the galaxy. A research team at the University of Tennessee, Knoxville, will follow multidimensional computer simulations of the SiSB phase through the collapse/supernova phase in massive stars using state-of-the-art computational simulation codes to better understand this critical process for creating and dispersing atomic elements. The PI will present public lectures on supernova science and nucleosynthesis, or element creation, and train a graduate student in both stellar astrophysics and large-scale computation.The research team will simulate the developments in the last hour of convective silicon shell burning in a massive star and continue the simulations into the supernova explosion phase. The team will run a multi-dimensional code with realistic microphysics, including nucleosynthesis, neutrino transport, and turbulent convection. Since the code runs in three dimensions, they will be able to introduce asymmetries, which are known to be important, particularly for the supernova neutrino heating mechanism. The pre-collapse burning models will explore the limits of dimensionality, spatial resolution, nuclear network completeness, and duration required to adequately capture this dynamic stellar phase. The explosion simulations will calculate the element production from the supernova along with neutrino and gravitational wave signals. The proposed work will use a simulation code called Chimera, which the PI describes as a combination of three separate mature codes covering three aspects of the problem.

大质量星星（大于太阳质量的9倍）生命的最后阶段是硅的核聚变（“燃烧”），在惰性铁芯周围的壳中产生铁，增加铁芯的质量。 这个阶段可以持续一个小时，直到铁核的生长引发它的坍缩，成为一个被吸积物质包围的致密的中子星星（NS）。 由新NS发射的亚原子粒子称为中微子加热物质，并将其在冲击波阵面中通过周围的星星驱动，产生超新星爆炸，将新制造的元素送入星系的星际介质。 位于诺克斯维尔的田纳西大学的一个研究小组将使用最先进的计算模拟代码，通过大质量恒星中的坍缩/超新星阶段，对SiSB阶段进行多维计算机模拟，以更好地理解创建和分散原子元素的关键过程。 PI将举办超新星科学和核合成或元素创造的公开讲座，并培养一名恒星天体物理学和大规模计算的研究生。研究团队将模拟大质量星星中对流硅壳燃烧最后一小时的发展，并继续模拟到超新星爆炸阶段。 该团队将运行一个具有现实微观物理学的多维代码，包括核合成，中微子传输和湍流对流。 由于代码在三维空间中运行，他们将能够引入不对称性，这是已知的重要性，特别是对于超新星中微子加热机制。 塌缩前燃烧模型将探索维度、空间分辨率、核网络完整性和充分捕获这种动态恒星相所需的持续时间的限制。 爆炸模拟将计算超新星沿着中微子和引力波信号产生的元素。 拟议的工作将使用一个名为Chimera的模拟代码，PI将其描述为三个独立的成熟代码的组合，涵盖问题的三个方面。