INSPIRE: STAR: Scalable toolkit for Transformative Astrophysics Research

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This INSPIRE award is partially funded by the Stellar Astronomy and Astrophysics Program in the Division of Astronomical Sciences in the Directorate for Mathematical and Physical Sciences, by the Software and Hardware Foundations Program and the Information Technology Program in the Division of Computing and Communication Foundations in the Directorate for Computer and Information Science and Engineering, and by the Experimental Program to Stimulate Competitive Research in the Office of Integrative Activities.This award will support a large-scale computational effort to model the disruption and merger of white dwarf stars. The major goal is to include significantly improved physical realism than in current models. White dwarf stars are the low-mass endpoints of stellar evolution for stars like the Sun. Many of these are found in close binary systems, and it is well known that such close binaries will merge on time scales of 1 to 10 billion years. White dwarf mergers have recently been proposed as an important additional production channel for Type Ia supernovae, which are the most important probes of the expansion of the universe. The merger process and subsequent explosion requires that a large number of physical processes all be modeled at once, including magnetohydrodynamics, nucleosynthesis, radiative transport, and rapidly-changing gravitational fields. These various processes have quite different natural length, time, and density scales, and the level of complexity required for highly realistic modeling of stellar mergers is not achievable in current codes.The project will require advances in computational techniques. One of the key goals is to improve performance of multi-physics simulations on massively parallel architectures, which is currently limited by problems of scale and overhead in data distribution and resource allocation. The effort will explore the various tradeoffs between overhead and parallelism, and will enable improved strategies in order to enable more efficient and more scalable computation for astrophysical and other problems.The project is expected to have a broad applicability of the project?s computational techniques beyond the direct problem of stellar mergers. A number of related problems in stellar astrophysics also require integrating the treatment of fluid dynamics, dynamic gravity, thermal and radiative transport, and nuclear energy generation. The group anticipates that the largest direct impact will come in the areas of supernova explosion modeling, the mergers of stars of various types, and stellar evolution when tidal effects and rotation are important.