Place: 4421 Sterling Hall, Coffee and Cookies at 3:30 pm, Talk starts at 3:45 pm
Speaker: Paul Woodward, University of Minnesota
Abstract: Over the last several years, I have been simulating stellar interiors with a 3-D compressible hydrodynamics code, PPMstar. This work is a collaboration between my team at the University of Minnesota and the team of Falk Herwig, at the University of Victoria in Canada. This work focuses on the process of material mixing at the boundaries of convection zones and their potential effects upon stellar evolution. Through such mixing processes, small concentrations of nuclear fuels can be carried downward in convection zones into regions that are much hotter, where they can burn very rapidly with significant energy release. In the last two years, we have been looking at this process in massive main sequence stars, where entrainment of hydrogen fuel into the core convection zone can extend the star's main sequence life. In the case of these main sequence stars, we have observations of asteroseismology to compare with to validate our results. We obtain mixing rates that are consistently on the high side of our expectations. This has led us to explore the effects of rotation of these stars on this convective boundary mixing. I will present results of simulations of a massive star rotating at different rates and discuss how these simulations reveal the development of more rapidly rotating equatorial jets near the top of the central convection zone, with correspondingly less rapidly rotating central regions. The behavior of internal gravity waves in the stably stratified gas above the convection zone will also be discussed, with a focus on angular momentum transport.
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