Modeling Nature's Biggest Bombs: Type Ia Supernovae Stan Woosley, UCSC

At its heart, understanding a Type Ia supernova requires modeling turbulent nuclear combustion at near infinite Reynolds number (Re ~ 10**14) and large Lewis number (Le ~ 10,000) on a large range of length scales. There are four principal sub-problems, each of which has eluded solution for decades, but can be addressed by large scale simulation. First, is the ignition. Where and how often is burning ignited in the convective core of an exploding white dwarf star? The outcome is known to be sensitive to the initial conditions near the center of the star, which may well be chaotic. Second is the propagation of the flame, both in the flamelet and distributed regimes. Until near the end, the flame is an unresolvably narrow sheet whose motion must be determined by a subgrid model, yet how fast it moves determines the strength and brightness of the explosion. Third is whether and how the subsonic burning makes a spontaneous transition to a detonation. Observations favor this outcome, but the physics of the transition has been obscure. Fourth, is the radiation transport. Why does the supernova look the way it does and can its light curve really be relied upon to do precision cosmology? Our Consortium has made genuine progress in each of these areas, as well as in planning, with observers, future observational strategies for SNAP/JDEM and LSST. A new generation of codes is being optimized for the four tasks and preliminary results will be presented.