Introductory Astronomy: Type II Supernovae

Type II supernovae occur when the iron core of a supergiant star collapses due to gravity. This causes the outer layers to fall inward, bounce off the core, and explode outward as a supernova.

Type II supernovae are characterized by the lack of hydrogen lines in their spectrum. The maximum magnitude of their lightcurves is about -17, but this relation is not as exact as type I supernovae. Type II lightcurves also differ from type I lightcurves in appearance as time passes. Type II supernovae are also characterized by the emission of neutrinos (produced by the collapsing core of the star) just before the explosion.