Institution(s): 1. Geneva Observatory
Mass loss has a profound impact on the evolution and fate of massive stars. Recent observations have shown that massive stars may lose significant amounts of mass during their late stages before core collapse. In this talk, I will discuss radiative transfer modeling of supernovae observed early enough that dense regions of the progenitor wind could still be detected. I will focus on the progenitors of SN 2013cu and 1998S, which we propose to arise from the explosion of unstable luminous blue variables, yellow hypergiants, or red supergiants undergoing extreme mass loss events. I will show how the mass loss, wind velocity, and chemical abundances of stars at the pre-explosion stage can be directly constrained using the radiative transfer code CMFGEN to model early-time supernova spectra, with similar accuracy as for hot massive stars.