Stars
Contents
Image: The Sun, a perfectly
ordinary Yellow Dwarf star
Credit: NASA/JSC/Skylab
Overview
A star is an immensely large, self luminous object consisting mostly of plasma or degenerate matter.
Star birth and formation
When a large star dies it may produce a supernova. These supernova form clouds of nebulous gas and dust.
Stars begin their life as clouds of nebulous gas and dust remnants left over from these great explosions
These gas clouds accrete and bond together to form a rotaing disc. Heavier material tends to travel inward as mass increases in the centre of the disc
Immense pressures are created as gravity forces more and more matter together until even the bonds between individual atoms are broken down. Nuclear fusion takes place and a star is born
Types of stars
Main Sequence star
This is a very common type of star. Most stars will go through the main sequence stage once nuclear fusion reactions start. Throughout the life of the star there will be a constant 'Tug-of-War' between the mass of the star trying to contract under the force of gravity and pressure of gases expanding the star. Main sequence stars can 'burn' for many billions of years.
Red Giant
A former main sequence star which as used up its supply of hydrogen and starts convert helium into carbon. The star will swell to many times its original size.
