One of the most massive cosmic explosive events in the universe is a supernova. A supernova is the violent death of a luminous supergiant star. These blindingly bright star bursts occur at the end of a star’s lifetime, when its nuclear fuel is exhausted and it is no longer supported by the release of nuclear energy.
If the star is particularly massive, then its core will collapse and in so doing will release a huge amount of energy. This will cause a blast wave that ejects the star’s envelope into interstellar space. Astronomers originally classified supernovae into two “types”, I and II. Type I had no hydrogen emission lines in their spectra whereas Type II exhibited hydrogen emission lines. Later it was realized that there were in fact three quite distinct Type I supernovae, now labelled Type Ia, Type Ib and Type Ic.
Supernovae play a fundamental role in a great cosmic recycling program. We believe that almost all of the elements in the Universe that are heavier than hydrogen and helium are created either in the centres of stars during their lifetimes or in the supernova explosions that mark the demise of larger stars.