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General numerical fluid dynamics algorithm for astrophysical applications

Description: Finite difference simulation of fluid flows under astrophysical conditions is often complicated by factors such as complex gas physics, the occurrence of dynamics at widely differing length scales, and the necessity of using implicit difference equations. This report describes a simple, general, and efficient algorithm for solving one-dimensional, spherically symmetric problems using a variation of the ICED-ALE method. A computer code named VEGA has been written based on this algorithm, and the early stages of the collapse of a one-solar mass protostellar cloud are presented as a sample solution. (auth)
Date: October 1, 1975
Creator: Ruppel, H.M. & Cloutman, L.D.
Partner: UNT Libraries Government Documents Department

Numerical study of rotating relativistic stars

Description: The equations of structure for rotating stars in general relativity are presented and put in a form suitable for computer calculations. The results of equilibrium calculations for supermassive stars, neutron stars, and magnetically supported stars are reported, as are calculations of collapsing, rotating, and magnetized stars in the slowly changing gravitational field approximation. (auth)
Date: August 25, 1975
Creator: Wilson, J.R.
Partner: UNT Libraries Government Documents Department

Neutrino flow and gravitational collapse

Description: The discovery of neutral currents in neutrino interactions has made necessary the recalculation of the neutrino flow during stellar collapse. Neutral currents cause a coherent scattering cross section of complex nuclei proportional to the square of the atomic weight. This allows neutrinos to escape easily from the hot, dense center where only free baryons exist. The neutrinos then interact strongly in the outer region of high atomic weight and, under certain circumstances, produce a supernovae-like explosion in the outer reaches of the star, leaving a neutron star behind. For an explosion to occur, the scattering in the envelope of heavy nuclei must be greater than the scattering of the free baryons in the core. In particular, with Friedman's interpretation of Weinberg's theory, the cross section ratio is insufficient to produce an explosion. Other theories state that suppressing the free baryon cross section does lead to an explosion. (auth)
Date: August 18, 1975
Creator: Wilson, J.R.
Partner: UNT Libraries Government Documents Department