Round table on stellar evolution: rotation, magnetic field or what?

Abstract
Rotation and mass loss appear to resolve many problems remaining in the evolution of massive stars. But, we may wonder whether magnetic fields are important or not. Some first effects of the magnetic fields created by the Tayler-Spruit dynamo for massive stars are shown. As it stands presently, the theory does not agree well with observations. Thus, either magnetic fields are of little importance in massive stars or the dynamo theory needs to be further improved.