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3-D Stellar Hydrodynamics Simulations for Convective-Reactive Nucleosynthesis

对流反应核合成的 3-D 恒星流体动力学模拟

基本信息

批准号：
1713200
负责人：
Paul Woodward
金额：
$ 1.89万
依托单位：
University of Minnesota-Twin Cities
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：
2017-09-01 至 2018-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1713200&HistoricalAwards=false
关键词：
Stellar Hydrodynamics Simulations Convective Reactive

项目摘要

Astronomical observations are now probing the early stages of the universe, in which galaxies developed and merged, and the formation of structure in the universe and its evolution to the present era was set in motion. An important part of this story is the chemical evolution of galaxies. The formation of the elements in stars and their subsequent dispersal are powerful tracers of structure formation and evolution. This project will simulate on Blue Waters processes deep inside stars that play an important role in the heavy elements they generate. These processes are driven by mixing of gases at the boundaries of convection zones, which can bring new fuels into a convection zone, carrying them down into much hotter regions where they burn very rapidly and activate nuclear reaction networks in a special convective-reactive regime. In this regime, reacting nuclei are transported by the turbulent convection flow on about the same timescale as the reactions take place, so that significant departures from spherical symmetry, even in a statistical sense, can result. This project will use the petascale capabilities of Blue Waters to simulate these brief events in 3D.This project we will build on earlier work on Blue Waters to study a process where the O-shell convection zone in a massive star can work its way to the base of the C-shell convection zone above, leading to ingestion of carbon fuel and an ultimate merger of the two burning shells. The project will compute the resulting nucleosynthesis by following the concentrations of a large number of nuclear isotopes and computing their interactions on a 4-D grid of reduced resolution in space and time. A fine grid is required to accurately advance the turbulent convection flow and to compute the amount of fuel entrained in it at the convection zone boundary. The study will follow the most important species on this fine grid, but will represent on the coarser grid the large number of nuclear reactions from which energy release is minor and has minimal back reaction on the flow. This project will generate a large database of results from the 3-D simulations on Blue Waters of convective boundary mixing in stellar interiors. The project intends to organize this database so that the simulation codes can mine it automatically, comparing it to a variety of potentially useful 1-D models of the mixing process. In terms of broader impacts, the project will make this database and tools available to the community on-line in a useful format, so that it will enable research by many others. In addition, the project will work with the NuGrid collaboration to see that the results are incorporated into data sets that are available to the community for chemical evolution simulations of galaxies and structures in the early universe.

天文观测现在正在探索宇宙的早期阶段，在这一阶段，星系发展和合并，宇宙结构的形成及其演变到现在的时代已经开始。这个故事的一个重要部分是星系的化学演化。恒星中元素的形成及其随后的扩散是结构形成和演化的有力示踪剂。该项目将模拟恒星内部深处的蓝色沃茨过程，这些过程在它们产生的重元素中起着重要作用。这些过程是由对流区边界处的气体混合驱动的，这可以将新的燃料带入对流区，将它们带到更热的区域，在那里它们非常迅速地燃烧并在特殊的对流-反应机制中激活核反应网络。在这种情况下，反应核被湍流对流在与反应发生相同的时间尺度上输送，因此即使在统计意义上，也可能导致与球对称性的显著偏离。这个项目将使用Blue沃茨的千万亿次能力来模拟这些短暂的3D事件。这个项目我们将建立在Blue沃茨早期的工作基础上来研究一个过程，在这个过程中，大质量星星中的O壳层对流区可以工作到上面的C壳层对流区的底部，导致碳燃料的摄入和两个燃烧的壳层的最终合并。该项目将通过跟踪大量核同位素的浓度并在空间和时间分辨率降低的四维网格上计算它们的相互作用来计算由此产生的核合成。需要精细网格来精确地推进湍流对流并计算在对流区边界处夹带在其中的燃料量。这项研究将遵循这个细网格上最重要的物种，但将代表在粗网格上的大量核反应，从这些核反应中释放的能量很小，对流动的反反应也很小。该项目将生成一个大型数据库，其中包含恒星内部对流边界混合的Blue沃茨三维模拟结果。该项目打算组织这个数据库，以便模拟代码可以自动挖掘它，将其与混合过程的各种潜在有用的一维模型进行比较。就更广泛的影响而言，该项目将以一种有用的形式向社区提供这一数据库和工具，以便使许多其他人能够进行研究。此外，该项目将与NuGrid合作，将结果纳入社区可用于早期宇宙星系和结构化学演化模拟的数据集。