1. Life Cycle of Stars Birth Place of Stars:
Dark and cold inter-stellar clouds
These clouds are made of more hydrogen than helium.
These clouds have very small amount of heavier elements.

2. Life Cycle of Stars Beginning;
Shock waves or any other trigger may cause contractions to begin
Gravity squeezes the particles in the nebula, pulling every particle towards the center.
As the process continues, gravitational energy is converted to thermal energy

3. Protostar The Initial contraction period may last for a million year.
The temperature of this body rises slowly until it is hot enough to radiate energy from its surface in the form of red wavelengths.
This large red object in the center is called the protostar.

4. Protostar to a Star
During protostar stage, gravitational contraction continues at a rapid pace.
This causes the center to heat more intensely than the outer layers.
When the core of a protostar reaches 10 million K, pressure within is so great that nuclear fusion of hydrogen begins.
A Star is born.

5. Star
Heat from the hydrogen fusion causes the increase in outward pressure.
This pressure is balanced by gravity.
This stage of the star is called the stable state or main sequence star stage.
Star spends most of its life in this stage.
As long as hydrogen is available to be fused the star will remain in that stable state.

6. Life Cycle of Stars Beginning of the End:
Stars begin to die when they run out of hydrogen
Gravity begins to take over
Star begins to shrink; outer core of hydrogen begins to fuse
Star gets bigger

7. Life Cycle of Stars Death of Stars:
What stars end up as depend on mass
Low and Medium mass stars
Planetary nebula white dwarf
High mass stars
Supernova neutron star or black hole

8. Life Cycle of Stars Death of Stars: Low and Medium Mass
Main Sequence Star
Red Giant
Planetary Nebula
White Dwarf

9. Life Cycle of Stars Death of Stars: High Mass Main Sequence Star
Red Super Giant
Supernova
Neutron Star
Black Hole

10. Life Cycle of Stars High Mass Stars: Mass greater than 8x our sun
Create high mass elements such as iron
Neutron Star
Formed if remaining star < 3x sun’s mass
Black Holes
Formed if remaining star > 3x sun’s mass

11. Black Holes What is a Black Hole??? Black Holes Info Sheet
An object so massive and dense that not even light can escape its gravity
The end result from a supernova of a star that has a mass greater than 3x the sun

12. Life Cycle of the Sun
As fusion begins to slow down, the core of the sun will contract
Temperature in the core will rise
The outer layers of the sun will expand, consuming in the inner planets
Sun will become a Red Giant

14. Life Cycle of the Sun
Core of the sun will begin to fuse helium into larger elements such as carbon and oxygen
Continuing over the next 100 million years…
Core will become entirely carbon and oxygen
Core will contract
Outer layers will expand
Outer layers will form a planetary nebula
Core of sun will become a white dwarf

15. Death of a Star
All stars run out of hydrogen and collapse due to gravity.
More massive stars burn their fuel quickly and end their lives as supernova.
Low mass stars do not reach the temperatures to start fusion, so they will remain red hot for billions of years.
Low mass stars end as white dwarfs

16. Death of Sun An Average Star
When fusion of lighter elements is not possible, outward pressure is reduced.
The core starts to contract, this cause the outer layers to expand.
This outer layer is made of gases and dust and is called the planetary nebula.
Core of the star heats up due to contraction,
This stage is called the white dwarf.
White dwarf finally cools down to become black dwarf