The Evolution of Stars- stars evolve in stages over billions of years

1. Nebula- interstellar clouds of gas and

dust undergo gravitational collapse and rotate forming a protostar

- increased pressure causes the temperature of the gas to rise and become plasma

- process of nuclear fusion takes place at 10,000,000oC forming a star

Nebula

Nebula

The Evolution of Stars2. Main Sequence Stars- the stage of life where a star is

fusing hydrogen into helium in its core

- approximately 95% of all knownstars (including our Sun) are in this stage

The Evolution of Stars3. Red Giants and Supergiants- form once stars have fused all the

hydrogen in their cores into helium - helium then fuses into heavier

elements such as carbon and oxygen

- it then expands and cools to become over 100 times the size of our Sun

The Evolution of Stars

4. The final stage in the life of a star is dependant on its birth mass:

Below five solar massesWhite Dwarf: remaining

matter into a hot, dense core surrounded by a planetary nebula

The Evolution of Stars

Above five solar massesSupernova: violent

explosion forming either a black hole (a region of space where gravity is so dense that even light cannot be emitted) or a neutron star