Stellar Evolution

It can take a star a million or even billions years. How long a star lives is dependent on the amount of the gas a star has which is related to mass. The gravity is pushing the star inward but the fusion that happens in the core allows for the star to produce energy outward and keep the star stable. A law mass star (average star) is the smallest possible size for star which can do nuclear fusion (about 13 Jupiter's).

Credit: ESO/M. Kornmesser

All types of stars start off with gas and dust which is part of a giant giant molecular cloud. After these gases come closer and tighter because of gravity it gets really hot and after it reaches a point it will start nuclear fusion and this will eventually create a main sequence star. Inside the stars protons start to combine and after beta decay (radioactive decay) a deuteron is formed and these combine to make helium. This is the hydrogen fusion core. The sun will continue to burn and as it burns the core will get smaller and it will produce faster and the outer layers will expand. These layers will slowly be cooled and this will make the star red but it is getting more hotter as time passes. The star is now a Red Star and itstars to shrink now and after the billions of years with only very little hydrogen and helium left, the core will collapse when it has carbon and oxygen in its core (carbon core). The star will start to expand and this will release a lot of energy and this only leaves the core and it is called the white dwarf star. The gas that was released and heat that was released will become a planetary nebula which is the starting point for many stars. In a high mass star starts of like a low mass star with the collection of more gas and particles and with the extra mass it is much more bigger and hotter because of faster fusion. With the faster fuel consumption of this high mass star it will die much faster somewhere in 10 million years. The star will slowly star to get bigger and the core will get a lot more hotter and this fusion will produce many elements like helium, oxygen, Neon, Silicon and Iron which is the heaviest element that is producible in a star. The star then become a red giant. After this the star's collapses and creates an explosion in a second and this is called the supernova. After a supernova is where many elements that is more heavier than iron is produced. After the supernova this star can either be a neutron star of a black hole. A neutron star is a star that contains a lot of metals.