Life Cycle of the Stars

The Making of the Star

• Stars are formed in nebulae, which are large clouds of dust and gas.

• Some of these clouds can get be up to 1 light year long, from base to tip.

• The majority of the gas in these stellar nurseries is hydrogen.

Gravity Pulls It Together• Gravity at the center of

the cloud pulls the dust together and starts to form a clump of matter.

• As the ball of matter gets bigger, the force of gravity becomes stronger.

• As the clump of matter grows, it begins to spin and heat up.

A Star is Born

• When the core of the matter becomes hot enough, thermonuclear fusion begins.

• This means that there is enough heat to turn hydrogen to helium.

• Once this has happened a true star has been born.

• The star shines with its own light.• A solar wind then blows away the rest of

the dust and gas.

The Death of a Star

• How a star ends its life depends on its mass or how much matter it was born with.

• Low and medium mass stars will end up as white dwarfs.

• Stars that started with a lot of mass may end their lives as black holes or neutron stars.

The Dying Star• When the star runs out of

helium to burn, the star starts to collapse.

• The star begins to collapse into itself. This collapse causes the star to compact.

• After several more nuclear processes the star burns all the remaining helium and loses its outer layers. Now, the compacted core is exposed to the universe.

The White Dwarf

• A White Dwarf is the end of the life cycle for Earth sized stars.

• They produce a white-hot glow.

Neutron Stars

• When a star that is the size of 10 to 20 solar masses runs out of fuel to burn, it explodes and the remaining matter collapses to become a neutron star.

• This compact star is a few kilometers in diameter and resembles a giant nucleus made of neutrons.

Black Holes

• When a star of more than 30 solar masses runs out of fuel, the collapse is so strong that no known force can stop it or resist it.

• This collapse happens at a single point.

• The matter of the star, its atoms and subatomic particles are squeezed out of existence, but the star remains its mass.

• Not even light can escape, that is why it is called a black hole.