Strange mode instabilities and mass-loss in evolved massive primordial stars

TL;DR

This study investigates the stability of evolved primordial massive stars, revealing that strange mode instabilities can induce pulsations and stellar winds, potentially affecting their evolution and mass-loss.

Contribution

It provides the first linear stability analysis of primordial stars in the 150-250 solar mass range, linking instabilities to mass-loss via stellar winds.

Findings

Strange mode instabilities occur below log T_eff = 4.5.

Instabilities lead to finite amplitude pulsations.

Mass-loss rates range from 7.7e-7 to 3.5e-4 solar masses per year.

Abstract

A linear stability analysis of models for evolved primordial stars with masses between 150 and 250 M$_{\odot}$ is presented. Strange mode instabilities with growth rates in the dynamical range are identified for stellar models with effective temperatures below log T$_{\rm{eff}}$ = 4.5. For selected models the final fate of the instabilities is determined by numerical simulation of their evolution into the non-linear regime. As a result, the instabilities lead to finite amplitude pulsations. Associated with them are acoustic energy fluxes capable of driving stellar winds with mass-loss rates in the range between 7.7 $\times$ 10$^{-7}$ and 3.5 $\times$ 10$^{-4}$ M$_{\odot}$ yr$^{-1}$.