  Massive stars becoming red supergiants lose a significant amount of their
mass during that brief evolutionary phase. They then either explode as a
hydrogen-rich supernova (SN Type II), or continue to evolve as a hotter
supergiant (before exploding). The slow, dusty ejecta of the red supergiant
will be over-run by the hot star wind and/or SN ejecta. I will present
estimates of the conditions for this interaction and discuss some of the
implications.
