Red Supergiants and Post-Red Supergiants – the Evidence for High Mass Loss Events

Abstract

The complex circumstellar environments associated with several of the most luminous cool supergiants provide evidence for episodic high mass loss events. The origin of the high mass loss is not understood but circumstantial evidence strongly suggests that large scale surface activity and magnetic fields are responsible. I briefly review the observational evidence from multi-epoch imaging and spectroscopy for the high mass loss events and instabilities in these stars. New results from high-resolution AO near and mid-IR imaging of VY CMa, IRC +10420 and μ Cep is also presented.