Spectrum of the type II-L supernova 1984E in NGC 3169 Further evidence for a superwind

Optical spectra near the maximum light of the type II-L supernova 1984E in NGC 3169 reported by Gaskell (1985) and Dopita et al. (1984) contained narrow Balmer line profiles which showed that the explosion took place inside a dense circumstellar shell. Spectrophotometric data obtained a month after maximum light, which show little or no emission from the circumstellar shell, are presented. If the shell was swept up by the expanding ejecta within a month of maximum light, it must have been produced within the last 200 years before the supernova explosion. Either of the alternative possibilities for the origin of type II-L explosions might be able to account for a brief superwind prior to the explosion. 16 references