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 (\dot{M}) 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 \dot{M} values for the RSGs in two Galactic clusters (NGC 7419 and χ Per) where the RSGs are all of similar initial mass (M_initial ∼ 16 M_⊙), allowing us to study how \dot{M} changes with time along an evolutionary sequence. We find a clear, tight correlation between luminosity and \dot{M} 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 \dot{M} prescriptions currently used in evolutionary models.