Evolution of massive stars with pulsation-driven superwinds during the RSG phase

TL;DR

This study explores how pulsation-driven superwinds in red supergiants influence their late-stage evolution, potentially causing significant mass loss and affecting supernova progenitor characteristics.

Contribution

It provides the first detailed models linking pulsation growth rates to superwind episodes and their impact on massive star evolution.

Findings

Stars can undergo runaway mass loss episodes due to pulsation-driven superwinds.

Massive stars may lose large fractions of their hydrogen envelopes before supernova.

This process could explain the observed upper mass limit for Type II-P supernova progenitors.

Abstract

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