EVOLUTION OF MASSIVE STARS WITH PULSATION-DRIVEN SUPERWINDS DURING THE RED SUPERGIANT PHASE

Abstract

Pulsations driven by partial ionization of hydrogen in the envelope are often\nconsidered important for driving winds from red supergiants (RSGs). In\nparticular, it has been suggested by some authors that the pulsation growth\nrate in a RSG can be high enough to trigger an unusually strong wind (or a\nsuper-wind), when the luminosity to mass ratio becomes sufficiently large.\nUsing both hydrostatic and hydrodynamic stellar evolution models with initial\nmasses ranging from 15 to 40 \\Msun, we investigate 1) how the pulsation growth\nrate depends on the global parameters of supergiant stars, and 2) what would be\nthe consequences of a pulsation-driven super-wind, if it occurred, for the late\nstages of massive star evolution. We suggest that such a super-wind history\nwould be marked by a runaway increase, followed by a sudden decrease, of the\nwinds mass loss rate. The impact on the late evolution of massive stars would\nbe substantial, with stars losing a huge fraction of their H-envelope even with\na significantly lower initial mass than previously predicted. This might\nexplain the observed lack of Type II-P supernova progenitors having initial\nmass higher than about 17 \\Msun. We also discuss possible implications for a\nsubset of Type IIn supernovae.\n