What is a Supernova?

This is a vast explosion, destroys an entire star. Seen in distant galexies, they are hard to study. When they occur in nearby galexies studies can take place more readily.

The last huge Supernovea seen in our galexy, was seen by Kepler in 1604. Sinse then the brightest Supernovea in the southern sky was was 1987A. In the northern sky, the brightest was 1993J. They fell into two different groups.

Type 1 results from the tranfer of mass inside a binary (or two star system) which consists of a white dwarf star and a giant star. In general type two supernovea are a single massive star which end in a spectacular light show.

White Dwarf Star

This is a star, about the size of Earth, however it weighs as much as the Sun. It is prevented from shrinking. Electrons that are free can be packed so close together. In more massive stars the barrier can be broken when protons combine with their electron counterparts. The first white dwarf was the companion to Serius. They are in the same orbit. They are both equal to the Sun in size. They are hard to detect because they are so dim. This is the last phase of a medium mass star.

Pulsars

These were discovered in 1967 by Jocelyn Bell and Anthony Hewish at The Radio Astronomy Observatory, (now the Nuffield Radio Astronomy Observatory at Cambridge. Radio emissions are extremly distinctive. There regularity is so great observers can predict there arrival down to a millisecond.