2020ApJ...889...86W

It has been well established from a variety of observations that red supergiants (RSGs) lose a lot of mass in stellar wind. Dust that has formed in this emitted gas over a few decades before core-collapse can lead to substantial extinction and obscure the intrinsic luminosity of the progenitor RSG. This may lead to a difficulty in determining the range of progenitor masses that lead to the different classes of supernovae. Even nearby, well-studied supernovae with pre-explosion observations, such as SN 2013ej, may suffer from this uncertainty in the progenitor mass. We explore here two different masses proposed for its progenitor. We compute their pre-supernova characteristics using Modules for Experiments in Stellar Astrophysics. We show that a non-rotating star with an initial mass of 26 M_☉ would require a considerable amount of circumstellar medium (A_V ∼ 3) to obscure its high luminosity given the observed pre-explosion magnitudes detected by the Hubble Space Telescope (HST). Such a high value of visual extinction appears to be inconsistent with that derived for SN 2013ej as well as SN 2003gd in the same host galaxy, M74. In contrast, the evolutionary models of a lower mass (13 M_☉) star are easily accommodated within the observed HST magnitudes. Some of the 26 M_☉ simulations show luminosity variation in the last few years, which could be discriminated by high-cadence and multiband monitoring of supernova candidates in nearby galaxies. We demonstrate that our calculations are well resolved with adequate zoning and evolutionary time steps.