Some statistical properties of type I supernovae

A list of wavelength measurements is compiled from the literature on the 6130 A absorption feature in the spectra of 16 type I (SN I) supernovae, and the corresponding matter velocities at the photosphere are used to test the validity of proposed subclassifications of SN I. While it is found that the slow and fast subclasses defined by Barbon (1973, 1975, 1980) on the basis of light curve properties have significantly different expansion velocities, the data suggest that SN I form a continuous sequence rather than two discrete subclasses, confirming Pskovskii's (1969, 1977) conclusion that expansion velocity and peak absolute magnitude are correlated with the rate of decline of the postpeak light curve.