The evolution of red supergiant mass-loss rates

The fate of massive stars with initial masses >8 M⊙ depends largely on the mass-loss rate (⁠|Ṁ|⁠) in the end stages of their lives. Red supergiants (RSGs) are the direct progenitors to Type II-P core collapse supernovae (SNe), 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 |Ṁ| values for the RSGs in two Galactic clusters (NGC 7419 and χ Per) where the RSGs are all of similar initial mass (Minitial ∼ 16 M⊙), allowing us to study how |Ṁ| changes with time along an evolutionary sequence. We find a clear, tight correlation between luminosity and |Ṁ| 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 16 M⊙ 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⊙. This is much less than expected for |Ṁ| prescriptions currently used in evolutionary models.