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含量的基础。美国国家科学院最近的一份报告《将夸克与宇宙联系起来：新世纪的11个科学问题》指出，元素的创造，特别是铁以外的元素的创造，是现代科学面临的最重要的问题之一，也掩盖了人类努力回答的最基本问题之一的答案：“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，有已知的系统效应和缺失的物理学抑制了“标准丰度蜡烛”的创建。大质量恒星的模型长期以来一直使用球对称，并使用对流和参数化爆炸的混合长度处理。最近在理解三维，可压缩，多流体，对流与核燃烧的突破提供了一个改进的处理对流和非对流混合恒星演化。此外，对单个核心坍缩超新星的观测表明，它们中的一部分是强不对称的。在这里，Young博士和合作者将对大质量星星的演化进行系统的调查（1）使用3D对流研究的新结果，（2）其超新星丰度产量是从3D爆炸模型计算的。这些产量和演化轨迹将与现有和未来的恒星和恒星种群丰度测定进行验证。分析的方法和技术将结合成一个有效的管道，包括分析方法，恒星演化模型，多维坍缩和爆炸模拟，以及用大型核反应网络对爆炸进行后处理，以建立详细的丰度水平。预计这项研究的结果将大大改进目前和未来的仪器，如斯皮策的“调查银河系演变的因素”和美国航天局的“空间干涉测量使命”对丰度测定的定量解释，这项研究将对物理学和天文学的若干领域产生影响，并促进国家/国际伙伴关系。本科生和研究生将参与并接触到一个跨学科的科学过程。这项工作的结果将纳入杨博士为本科非科学专业开设的大班，并通过讲座和文章向公众传播。最后，本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软件包发布。

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.