Institute for Advanced Study Informal Astrophysics Seminar

In dilute plasmas, the electron mean free path is significantly larger than the electron Larmor radius. As a result, heat is transported primarily along (not across) magnetic field lines. The physics of buoyancy instabilities ("convection") is dramatically modified in the presence of anisotropic heat conduction. For a weak magnetic field, a plasma is buoyantly unstable regardless of the sign of the temperature gradient. I describe the linear physics of these magnetically-mediated buoyancy instabilities and their nonlinear saturation. I then discuss the application of these instabilities to several astrophysical systems, including clusters of galaxies, accretion flows onto compact objects, and cooling white dwarfs and neutron stars.