The evolution of Red Supergiant mass-loss rates

TL;DR

This study investigates how mass-loss rates in red supergiants evolve with luminosity and initial mass, using IR data and radiative transfer modeling to refine estimates of stellar mass loss during the RSG phase.

Contribution

The paper provides new empirical measurements of mass-loss rates in RSGs with similar initial masses, revealing a tighter luminosity- correlation and suggesting current models overestimate mass loss.

Findings

Mass-loss rate correlates tightly with luminosity.

Stars of initial 16M lose about 0.61 M_ during RSG phase.

Current  prescriptions overpredict mass loss.

Abstract

The fate of massive stars with initial masses >8M$_\odot$ depends largely on the mass-loss rate (\mdot ) in the end stages of their lives. Red supergiants (RSGs) are the direct progenitors to Type II-P core collapse supernovae (SN), but there is uncertainty regarding the scale and impact of any mass-loss during this phase. Here we used near and mid-IR photometry and the radiative transfer code DUSTY to determine luminosity and \mdot\ values for the RSGs in two Galactic clusters (NGC 7419 and $\chi$ Per) where the RSGs are all of similar initial mass ($M_{\rm initial}$$\sim$16M$_\odot$), allowing us to study how \mdot\ changes with time along an evolutionary sequence. We find a clear, tight correlation between luminosity and \mdot\ suggesting the scatter seen in studies of field stars is caused by stars of similar luminosity being of different initial masses. From our results we estimate how much mass a 16M$_\odot$ star would lose during the RSG phase, finding a star of this mass would lose a total of 0.61$^{+0.92}_{-0.31}$M$_\odot$. This is much less than expected for \mdot\ prescriptions currently used in evolutionary models.