A Model for Eruptive Mass Loss in Massive Stars

Abstract

Eruptive mass loss in massive stars is known to occur, but the mechanism(s) are not yet well understood. One proposed physical explanation appeals to opacity-driven super-Eddington luminosities in stellar envelopes. Here, we present a 1D model for eruptive mass loss and implement this model in the MESA stellar evolution code. The model identifies regions in the star where the energy associated with a local super-Eddington luminosity exceeds the binding energy of the overlaying envelope. The material above such regions is ejected from the star. Stars with initial masses of 10−100 M _⊙ at solar and SMC metallicities are evolved through core helium burning, with and without this new eruptive mass-loss scheme. We find that eruptive mass loss of up to ∼10 ^−2 M _⊙ yr ^−1 can be driven by this mechanism, and occurs in a vertical band on the H-R diagram between $3.5\lesssim \mathrm{log}({T}_{\mathrm{eff}}/{\rm{K}})\lesssim 4.0$ . This predicted eruptive mass loss prevents stars of initial masses ≳20 M _⊙ from evolving to become red supergiants (RSGs), with the stars instead ending their lives as blue supergiants, and offers a possible explanation for the observed lack of RSGs in that mass regime.

Keywords

• Stellar physics
• Stellar winds
• Stellar evolution