Radial pulsation runaway in massive red supergiants in late evolutionary stage and implications to hydrogen-rich supernovae

ABSTRACT Performing a series of hydrodynamic stellar evolutionary simulations with mesa (Module for Experiments in Stellar Astrophysics), we investigate the excitation and growth of radial pulsations of massive red supergiants (RSGs) with the initial mass range of $M_\mathrm{ini}=13$–$18\, \mathrm{M}_\odot$. We show that strong radial pulsations develop in the hydrogen-rich envelope in their late evolutionary stages, and eventually the surface radial velocity exceeds the escape velocity for higher mass models. On the other hand, lower mass models exhibit more moderate pulsations with finite-velocity amplitudes and are expected to keep massive hydrogen-rich envelopes when they evolve toward the gravitational collapse of the iron core. While the latter group ends up as a familiar transient population of exploding RSGs, i.e. type IIP supernovae (SNe), the former group may expel a part of their envelopes and explode as different transients population. We investigate how the energy of the oscillating envelope is dissipated and released as radiation. We also empirically determine the condition for the pulsation-driven mass ejection in terms of the luminosity-to-mass ratio, $L/M>10^{3.9}\,\mathrm{L}_\odot /\mathrm{M}_\odot$. The corresponding luminosity threshold for the explored mass range may explain the observationally inferred constraints on type IIP SN progenitors.