Red supergiants in M31, M33, SMC and LMC

Evolutionary models show that the total amount of mass lost in this phase determines if these stars evolve to warmer temperatures before undergoing core collapse. The current Geneva evolutionary models mimic episodic mass loss by enhancing the quiescent prescription rates whenever the star's outer layers exceed the Eddington luminosity by a large factor.

This results in a 20M_{sun}_ model undergoing 10x more mass loss than it would otherwise, but has little effect on models of lower mass. We can test the validity of this approach observationally by measuring the proportion of high-luminosity RSGs to that predicted by the models. To do this, we use our recent luminosity-limited census of RSGs in M31 and M33, making modest improvements to membership, and adopting extinctions based on the recent panchromatic M31 and M33 Hubble surveys.