Lifecycles of Stars

Each star is…. born, goes through it’s lifecycle and dies

How long a star lives depends on its…. MASS

The greater the Mass, the shorter the star’s life. Think about a Hummer and a mini Cooper….which goes through its fuel faster?

All Stars begin the same way…..1. A star begins as a nebula (large amount of gas and dust) spread out in an immense volume. Crab NebulaOrion Nebula

Protostar 2. Gravity pulls some gas and dust together to form a Protostar (this is when nuclear fusion begins and is the earliest stage of a star’s life).

3. The star continues to use hydrogen for nuclear fusion. It is now a main sequence star.

4. What happens next depends on the mass of the star…..

Small or Medium Stars 5. When small or medium stars use up their fuel, their outer layers expand forming a red giant.

6. The outer layers eventually drift off and the remaining blue-white glowing core is called a white dwarf Size of Earth with mass of the Sun

Massive stars 7. If the star was massive, it will become a red giant or supergiant when it uses up its fuel. Nuclear fusion can not continue past Iron (Fe)

8. The supergiants can explode (supernova)

9. After the supernova, the remains of the star can form a dense neutron star ( up to three times the mass of the sun, but the size of an asteroid)

10. Some of the gas and dust can form a new nebula (and the process can begin again).

11. Only the most massive stars form black holes The gravity of this former star is so strong that not even light can escape.