Abstract
A simple model is developed in order to calculate the mass ejected by supernovae. We find that the 185, 1006, 1572 and 1604 AD events, all of them classified as either probable or possible type I supernovae, ejected between 0.1 and 0.4 solar masses with an expansion velocity of roughly 10 000 km s-1. This range of masses suggests that a collapsed object is at the center of the remnants produced by these supernovae if the precursor was a white dwarf whose mass was close to the limit. For the Crab we obtain an ejected mass of 0A5 M⊙ and point out that this value is not in contradiction with a proposal in which the moderate helium stars are good candidates for producing this kind of supernovae. Finally we obtain an ejected mass of 3.1 M⊙ for Cas A, indicating that a type II event produced this remnant. This ejected mass is close to what would be expected for a progenitor like an OBN star.
