Djehuty: A Virtual Observatory for Stellar Physics.

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Date/Time:Thursday, 22 Mar 2012 from 4:10 pm to 5:00 pm
Location:Room 18/19
Contact:Massimo Marengo
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Talk by David Dearborn, Lawrence Livermore National Laboratory

Until recently, essentially all previous research on stellar structure and evolution has assumed spherical symmetry, leaving important physical processes like convection, differential rotation, and magnetic fields to be treated through model approximation. Beyond that a majority of stars, including those thought to produce type 1a supernovae, are members of binary systems with significant 3-dimensional (3D) structures. The ability to compellingly answer many questions of stellar behavior has awaited the development of multidimensional capability. DJEHUTY is a full-featured 3D ALE radiation-hydrodynamics code that accounts for all the physical processes needed to describe stellar structure and evolution. It includes good models of the EOS and opacity of stellar material, as well as an extensive nucleosynthesis network. It operates in a massively parallel environment permitting previously impossible resolution. Djehuty has been used to study the Core Helium Flash, and to find an unexpected but long sought mixing process lowering the carbon isotope ratios in red giants. That research is continuing in collaboration with colleagues at Monash University, and I have begun a new effort to study the supernovae of the most massive stars with colleagues at the University of Texas.