Alan Calder:
Resolving Thermonuclear Supernovae

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Thermonuclear (Type Ia) supernovae are bright stellar explosions distinguished by light curves that can be calibrated to allow for their use as "standard candles" for measuring cosmological distances. While many fundamental questions remain, it is accepted that the setting of these events involves a white dwarf star (or two), and that the explosion is powered by explosive thermonuclear burning under degenerate conditions. Modeling these events presents a challenge because the outcome of an event sensitively depends on the details of the physics occurring on scales orders of magnitude smaller than the star. Such "microphysics" includes nuclear burning, fluid instabilities, and turbulence. I will give an overview of our understanding of thermonuclear supernovae and describe our approach to capturing these sub-grid-scale processes in macroscopic simulations.

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Professor Alan Calder is associate professor in Physics and Astronomy at Stony Brook University in New York, working in the nuclear physics of explosive astrophysical phenomena. With his extensive background in large-scale computing, he is deputy director of the Institute for Advanced Computational Science. He has held research appointments at the National Center for Supercomputing Applications and the University of Chicago at the Center for Astrophysical Thermonuclear Flashes. His research is principally in bright stellar explosions known as Type Ia supernovae which produce and distribute heavy elements and are therefore important for galactic chemical evolution, and whose light curves can be used as distance indicators for cosmological studies of the expansion of the universe. His simulations explore how stellar age and composition affect the event’s brightness which is critical to addressing their variability, which is a source of significant uncertainty in cosmology.