FURTHER ADVENTURES f OXYGEN BURNING IN A CONVECTIVE SHELL

摘要

Two-dimensional hydrodynamical simulations of a convective oxygen burning shell in the presuper- nova evolution of a 20 Mo star are extended to later times. We used the VULCAN code to simulate longer evolution times than previously possible. Our results confirm the previous work of Bazdn & Arnett over their time span (400 s). However, at 1200 s we could identify a new steady state that is significantly different from the original one-dimensional model. There is considerable overshooting at both the top and bottom boundaries of the convection zone. Beyond the boundaries, the convective velocity falls off exponentially, with excitation of internal modes. The resulting mixing greatly affects the evolution of the simulations. Connections with other works of simulation of convection, in which such behavior is found in a different context, are discussed.