The evolution of Red Supergiants to supernova in the LMC cluster NGC 2100

TL;DR

This study measures mass-loss rates of red supergiants in a coeval cluster to understand their evolution towards supernova, finding that mass-loss increases with evolution and impacts supernova progenitor models.

Contribution

It provides empirical measurements of mass-loss rates in RSGs within a single cluster, supporting existing prescriptions and challenging the need for increased mass-loss in stellar models.

Findings

Mass-loss rates increase as RSGs evolve.

Warm dust extinction is negligible in these stars.

Supports de Jager's mass-loss prescription for RSGs.

Abstract

The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova and dictate the appearance of the resulting explosion. To study how mass-loss rates change with evolution we measure the mass-loss rates (\mdot) and extinctions of 19 red supergiants in the young massive cluster NGC2100 in the Large Magellanic Cloud. By targeting stars in a coeval cluster we can study the mass-loss rate evolution whilst keeping the variables of mass and metallicity fixed. Mass-loss rates were determined by fitting DUSTY models to mid-IR photometry from WISE and Spitzer/IRAC. We find that the \mdot\ in red supergiants increases as the star evolves, and is well described by \mdot\ prescription of de Jager, used widely in stellar evolution calculations. We find the extinction caused by the warm dust is negligible, meaning the warm circumstellar material of the inner wind cannot explain the higher levels of extinction found in the RSGs compared to other cluster stars. We discuss the implications of this work in terms of supernova progenitors and stellar evolution theory. We argue there is little justification for substantially increasing the \mdot\ during the RSG phase, as has been suggested recently in order to explain the absence of high mass Type IIP supernova progenitors. We also argue that an increase in reddening towards the end of the RSG phase, as observed for the two most evolved cluster stars, may provide a solution to the red supergiant problem.