Rotation and angular momentum transport in stars – hydrodynamic processes

Mon, November 02, 2015

The recent wealth of information on the internal rotation of the Sun (and other stars) has made the problem of understanding rotation profiles and angular momentum transport inside these structures prominent in stellar physics. I will review the observational data and explain which challenges are presented to the theorist. Among these is the problem of the spreading of the tachocline, the narrow layer of strong shear between the radiative and convective zone. I will put forward a recent hydrodynamic model for this region which is compatible with the observations and simpler than the proposed alternatives. I will also discuss the Goldreich-Schubert-Fricke (GSF) instability, one of the many proposed causes of angular momentum transport which are incorporated in modern codes of stellar evolution. I will present preliminary results suggesting that the GSF instability is not so easily triggered, and its effects are far less important than currently thought.