Key points are not available for this paper at this time.
High-quality optical spectra of the Type I supernova 1981b in NGC 4536 from the time of maximum light to 116 days later are presented. This supernova is compared photometrically with the Type I supernova 1972e in NGC 5253, and the two are found to be very similar. Synthetic spectra based on resonance scattering lines superposed on a continuum give excellent fits to the data. The spectra after maximum light are dominated by blends of permitted Fe II lines. The continuum temperature, as a function of time, is determined by optical and infrared fluxes. This allows a determination of the angular size of the continuum photosphere, which is found to increase until 30 days after maximum light and then to decrease. Analysis of the photometry and spectroscopy, together with the assumption that the explosion occurred 15 days before maximum light, leads to a distance of 28 + or - 8 Mpc. Implications of this for the extragalactic distance scale are presented. The implications of the observations for models of Type I supernovae are also discussed.
Branch et al. (Fri,) studied this question.