On the Ultraviolet Spectra of Type I Supernovae

Abstract

A synthetic-spectrum technique, applied previously to the interpretation of the optical spectra of Type I supernovae, has been extended to the maximum-light near-ultraviolet spectrum. Spectral features in the interval 2750-3450 A are suggested to be complex blends of overlapping P Cygni profiles produced by numerous Fe II and Co II lines. This interpretation, if correct, provides further evidence for radial composition mixing in classical Type I supernovae (Type Ia), and conflicts with suggestions that explosions of Wolf-Rayet stars are responsible for the recently emphasized supernova subclass, Type Ib.