The Turbulent Origin and Injection of the Elements

Arizona State University, Scottsdale AZ

Investigators

Abstract

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.