Tuesday 26 Sep 2017The Turbulent Diffusivity of Convective Overshoot

Dr. Daniel Lecoanet - Princeton

Physics 4th Floor 14:00-15:00

The mixing of the radiative zone of stars by an adjacent convection zone is one of the most fundamental unsolved problems of stellar evolution. Recently, it has been proposed that convective overshoot could dramatically influence the evolution of super asymptotic giant branch stars by mixing the fuel out of a carbon flame. If this occurs, the carbon flame will stall, leaving a "hybrid" white dwarf, which could explain recent supernova observations. We present simulations of convective overshoot in run with the pseudo-spectral code Dedalus. To study mixing by convective overshoot, we evolve a passive tracer field. The horizontal average of the passive tracer field quickly approaches a self-similar state. This self-similar solution allows us to derive a turbulent diffusivity, which can place useful constraints of convective mixing in stars.

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