Toward Self-consistent Angular Momentum Transport in Pulsating Massive Stars

I report on preliminary results from an ongoing project that explores angular momentum transport by unstable pulsation modes in massive stars. After briefly reviewing the underlying formalism for this transport, and describing a numerical code that implements it, I present an example simulation for a 5M(circle dot) model star. I show that prograde l = m = 2 g modes, unstable due to the iron-bump kappa mechanism, can spin down the surface layers of the star by 25% over a short (similar to 100-year) timescale. The resulting shear layer separating the surface from interior acts to switch off the kappa-mechanism instability, providing a natural way of limiting mode amplitudes. This process may have a role to play in the mode selection mechanism of pulsating massive stars.