Massive star supernovae can be divided into four categories depending on the amount of mass loss from the progenitor star and the star ’ s radius : red supergiant stars with most of the H envelope intact ( SN IIP ) , stars with some H but most lost ( IIL , IIb ) , stars with all H lost ( Ib , Ic ) , and blue supergiant stars with a massive H envelope ( SN 1987A-like ) .
Various aspects of the immediate aftermath of the supernova are expected to develop in different ways depending on the supernova category : mixing in the supernova , fallback on the central compact object , expansion of any pulsar wind nebula , interaction with circumstellar matter , and photoionization by shock breakout radiation .
The observed properties of young supernova remnants allow many of them to be placed in one of the supernova categories ; all the categories are represented except for the SN 1987A-like type .
Of the remnants with central pulsars , the pulsar properties do not appear to be related to the supernova category .
There is no evidence that the supernova categories form a mass sequence , as would be expected in a single star scenario for the evolution .
Models for young pulsar wind nebulae expanding into supernova ejecta indicate initial pulsar periods of 10 - 100 ms and approximate equipartition between particle and magnetic energies .
Ages are obtained for pulsar nebulae , including an age of 2400 \pm 500 yr for 3C58 , which is not consistent with an origin in SN 1181 .
There is no evidence that mass fallback plays a role in neutron star properties .