Collaborative Research: Turbulence and Dynamics of Stars

该奖项将支持对理解超新星祖先和超新星爆炸前和爆炸后立即发生的超新星物理学问题的双管齐下的攻击。 第一个项目由亚利桑那大学的阿内特博士领导，将模拟大质量恒星铁核坍塌（II型超新星）之前的晚期演化阶段。 这将是第一次在三维空间中进行这种计算，并将涵盖核心坍缩开始的演变，包括对旋转和其他对称性破缺机制所起作用的评估。 这一时期的特点是湍流和核燃烧之间的复杂相互作用，决定了坍缩前核心的熵和密度结构，这沿着旋转是决定核心坍缩事件结果的重要特征。 第二项工作由亚利桑那州立大学的斯塔尔菲尔德博士领导，将探索白色矮星上的吸积作用，使用的成分从纯氦到不同丰度的重元素混合物。 这项工作的目标是确定导致Ia型超新星爆炸、高能氦闪光或氦新星的初始条件。 这项工作的动机是不方便的情况下，哪种星星产生Ia型超新星仍然是未知的，无论是理论和观测参数支持和反对各种方案只会变得更加复杂，在最近几年。这两个项目的共同点是一个数值代码，其中包括一个新的三维湍流对流理论，包括在空间维度和时间上的良好分辨率。该项目预计将通过发布恒星演化和对流代码影响更广泛的天体物理界。 该项目还将支持培训学生和一名博士后研究员，这项工作的成果将纳入这两个机构的课程。

This award will support a two-pronged attack on the problems of understanding supernova progenitors and of the physics of supernovae up to and immediately after the explosion. The first project, to be led by Dr. Arnett of the University of Arizona, will model the late evolutionary phase preceding iron core collapse (Type II supernovae) in massive stars. This will be the first time that such calculations have been done in three spatial dimensions, and will cover evolution to the onset of core collapse including an evaluation of the role played by rotation and other mechanisms of symmetry breaking. This epoch is characterized by a complex interplay between turbulence and nuclear burning that determines the entropy and density structure of the pre-collapse core, which along with rotation are important characteristics in determining the outcome of the core-collapse event. The second effort, led by Dr. Starrfield of Arizona State University, will explore accretion onto white dwarfs using compositions ranging from pure helium to a mixture with varying abundances of heavy elements. The goal of this work is to determine the initial conditions that lead either to a Supernova Type Ia explosion, an energetic helium flash, or helium novae. This work is motivated by the inconvenient situation that the kind of star producing Type Ia supernovae is still unknown, and both theoretical and observational arguments for and against various scenarios have only grown more complicated in recent years. Common to both projects is a numerical code that includes a new theory of turbulent convection in three-dimensions that includes good resolution in both spatial dimensions and in time. The project is expected to impact the wider astrophysical community through the release of stellar evolution and convection codes. The project will also support the training of students and a postdoctoral fellow, and the results of this work will be incorporated into the curricula at both institutions.