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**Session 27 - Variable Stars, Novae, & Supernovae.**

*Display session, Tuesday, June 10*

*South Main Hall, *

## [27.05] Multi-dimensional multi-group radiation-hydrodynamic models of convection in core collapse supernovae

*F. D. Swesty (UIUC)*
In recent years there has been wide recognition of the presence
of multi-dimensional convective phenomena in the post-bounce epoch of
core collapse supernovae. However, the numerical models of this
phenomena have often contained either cursory treatments of neutrino
transport or have made the assumption that the neutrino distribution
can be characterized as a Fermi-Dirac distribution parametrized by a
neutrino temperature and chemical potential. Recent work by
Mezzacappa et al. (1996) and Swesty (1996) have shown that these
assumptions can lead to substantial differences in the dynamics of the
convection. Furthermore the work by Mezzacappa et al. has shown that
the inclusion of multi-group neutrino transport may possibly hinder
the development of an explosion. In order to more accurately describe
the flow of neutrinos through the collapsing stellar core we have
developed a 2-D multi-group flux-limited-diffusion radiation
hydrodynamics code that fully couples the neutrinos to matter without
making assumptions about the neutrino distributions. The algorithm
employed in this code is a modification of the ZEUS-2D algorithm
developed by Stone, Norman, amp; Mihalas (1992). We present the results
of multi-group models we have conducted using this code. We will also
contrast the results of multi-group models to the results of gray
transport models, which assume a spectral distribution for the
neutrinos. Comparisons of both the dynamics of the matter and the
neutrinos will be made between the two classes of models. We will also
discuss the approximations that have to be made to include the
weak-interaction physics in each class of models. The models include
a realistic parameterized equation of state (EOS). We will discuss
parameter studies in which the nuclear force parameters have been
varied in the EOS. Finally, we consider multiple
progenitor masses in order to delineate the role of the
progenitor model in the dynamics of the collapse.

**Program
listing for Tuesday**