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Core Collapse Supernovae

Much of my work has been centered on developing better
models of the explosion mechanism of core collapse supernovae. This
is done by means of numerical radiation-hydrodynamic simulations
that are carried out on massively parallel computing platforms at the National
Center for Supercomputing Applications. These simulations rely on
computer programs that solve the equations of hydrodynamics and radiation
transport to model the flow of the gas in the star.
If you would like to see some movies resulting from
these simulations please click on the links below.

Here is a QuickTime movie depicting the evolution
of the entropy per baryon

of a post-collapse 15 solar mass star whose post-main-sequence
evolution was modeled by Woosley & Weaver. The hot material,
closer to the center of the collapsed stellar core is bouyant and rises,
while the colder material further out sinks. This rising/sinking
motion sets up a pattern of convection that is maintained until the gas
reaches a stable configuration.

And here is a QuickTime movie of the evolution
of the electron fraction of
the matter in the convective zone.

The electron fraction is the ratio of electrons to baryons
(i.e. neutrons & protons) in the matter. The electron
fraction changes as electrons are captured onto protons to form neutrons.
The yellow material further out is silicon or iron which has an electron
fraction of Ye=0.5 while the material at the base of the convection zone
has a much lower electron fraction. This change in chemical composition
is partially the cause, along with the entropy gradient, of the convection.

These simulations were carried out using a highly
modified version of the ZEUS-2D radiation hydrodynamics code developed
by Mike Norman and Jim Stone. The code models the flow of neutrinos through
the matter by solving the equations of flux-limited diffusion and the motion
of the matter by solving the Eulerian hydrodynamic equations. These
simulations are purely Newtonian but I am currently working on fully relativistic
models.

Copyright 2001 F. Douglas Swesty, all rights reserved
Doug Swesty /
douglas.swesty-AT-stonybrook.edu