supernova (Type II): A tremendous
explosion of an old star, which
increases in brightness by several
million-fold in only a few days. A
star must have at least eight times
the mass of the Sun to become
supernova. A supernova explosion
occurs when a star’s massive core
suddenly collapses to form an
ultra-dense neutron star or black
hole. The almost instantaneous
collapse of the stellar material heats
the gas to billions of degrees and
triggers a gigantic fusion explosion.
The energy output from a single
supernova is approximately equal to