Evidence for a radioactive decay hypothesis for supernova luminosity

VAN HISE1 has observed that the light curve for the Type I supernova 1937c is well represented by a sum of two exponentials with half lives which are ∼0.75 the half lives of 56Ni and 56Co in the β-decay chain 56Ni→56Co→56Fe. Colgate and McKee2 had previously suggested this chain as a source of supernova luminosity, but the hypothesis was not widely accepted because of the variability of the decay rates of supernova light curves and because the interstellar medium would bs overabundant in heavy elements. This letter presents observational evidence supporting a model of Leventhal and McCall3 which overcomes these difficulties.