The Turbulent Origin and Injection of the Elements

恒星产生的化学元素、光能和动能是星系演化和宇宙重子内容的基础。美国国家科学院最近的一份报告《连接夸克与宇宙：新世纪的十一个科学问题》指出，夸克元素的创造，特别是铁以外的元素，是现代科学面临的最重要的问题之一，并掩盖了人类努力回答的一个最基本的问题的答案：宇宙是由什么组成的？大质量恒星是宇宙中创造元素的主要引擎，是解开这一谜团的关键。然而，已知的系统效应和缺失的物理学阻碍了“标准丰度蜡烛”的产生。大质量恒星的模型长期以来一直使用球对称，并采用对流和参数爆炸的混合长度处理。最近在理解3D、可压缩、多流体、对流和核燃烧方面的突破，为恒星演化提供了对流和非对流混合的改进处理方法。此外，对单个核心坍塌超新星的观测表明，其中一些是强烈不对称的。在这里，杨博士和他的合作者将对大质量恒星的演化进行系统的调查(1)使用3D对流研究的新结果，(2)其超新星丰度产额是根据3D爆炸模型计算的。这些产额和演化轨迹将通过现有和未来的恒星和恒星群丰度测定来验证。分析的方法和技术将结合到一个有效的管道中，包括分析方法、恒星演化模型、多维坍塌和爆炸模拟以及爆炸的后处理和大型核反应网络，以建立详细的丰度水平。这项研究的结果有望显著改善目前和未来由斯皮策的“探测银河系演化的代理人”和美国宇航局的“空间干涉测量任务”等工具进行的丰度测定的定量解释。这项研究将对物理学和天文学的几个领域产生影响，并促进国家/国际伙伴关系。本科生和研究生将参与并接触一个跨学科的科学过程。这项工作的结果将被纳入杨博士为本科生非理科专业开设的大班，并通过演讲和文章向公众传播。最后，在该项目期间开发的软件将作为独立软件或与现有软件一起使用的包发布。

The production of chemical elements, luminous energy, and kinetic energy by stars is fundamental to the evolution of galaxies and the baryonic content of the cosmos. A recent National Academy report, "Connecting Quarks with the Cosmos: Eleven Science Questions for the New Century" identified the creation of the elements, particularly those beyond iron, as one of the most important problems facing modern science and concealing the answers to one of the most fundamental questions that humans strive to answer: "What is the Universe made of?". Massive stars hold a key to this mystery by serving as the main engines for creation of elements in the cosmos. However, there are known systematic effects and missing physics that inhibit creation of "standard abundance candles". Models of massive stars have long used spherical symmetry with mixing length treatments of convection and parameterized explosions. Recent breakthroughs in understanding 3D, compressible, multi-fluid, convection with nuclear burning have provided an improved treatment of convection and non-convective mixing for stellar evolution. In addition, observations of individual core-collapse supernovae suggest some fraction of them are strongly asymmetric.Here, Dr. Young and collaborators will undertake a systematic survey of massive star evolution (1) that uses new results from 3D convection studies and (2) whose supernova abundance yields are calculated from 3D explosion models. These yields and evolutionary tracks will be validated with existing and future abundance determinations of stars and stellar populations. Methods and techniques of the analysis will be combined into an efficient pipeline comprised of analytical methods, stellar evolution models, multi-dimensional collapse and explosion simulations, and post-processing of the explosions with large nuclear reaction networks to establish detailed abundance levels. The results of this study are expected to significantly improve quantitative interpretation of abundance determinations being conducted by current and future instruments such as Spitzer's "Surveying the Agents of a Galaxy's Evolution" and NASA's "Space Interferometry Mission".This research will have impacts on several areas of physics and astronomy as well as promoting national/international partnerships. Undergraduate and graduate students will be involved and exposed to a trans-disciplinary scientific process. Results from this work will be incorporated into Dr. Young's large classes for undergraduate non-science majors and disseminated to the public through talks and articles. Finally, the software developed during this project will be released as stand-alone software or as packages for use with extant software.