Life Cycle of a StarLife Cycle of a Star

Stars are born, live, and die. Just like people!

When a Star is Born

They are born in places called

Stellar Nurseries,

which are also called

Nebula

(Nebulae is the plural)

These are made of huge clouds of gas and dust.

Protostars

In Nebulae, gravity brings dust and gas and other things together,

and they make baby stars called

Protostars

Protostars are still growing. Gravity is still adding more and more gas and dust, making the

mass bigger.

Main Sequence Stars

Protostars keep growing and growing until gravity makes them stop.

Main Sequence Stars

It’s like blowing up a balloon as far as you can. Eventually, you must stop, because the balloon is as big as it can be.

Main Sequence Stars

When Protostars stop growing, they are called

Main Sequence Stars

This is the longest part of their life, and it’s like an “adult” star. It’s not a baby

or a child anymore.

Our sun is a main sequence star right now. It is about half way done its

main sequence period. The sun is about 4.5 billion years old, and most main sequence stars live to be about

10 billion years old.

A Star’s Death

The way a star dies depends on its size. Small stars, medium stars, and

large stars all die differently!

A Small Star’s Death

We don’t know.Small stars have a

reeeeeeeeaaaallllllllyy long main sequence period, and the small stars in the universe aren’t old enough to

die yet. So we haven’t seen any die. We don’t know what will happen.

A Medium Star’s Death

When a medium star dies, it will first expand and grow into a

Red Giant

Our sun will get so big that it will come and cover the Earth!

A Medium Star’s Death

A Big Star’s Death

A Big Star’s Death

Neutron Stars

P + E = N1 + -1 = 0

Black Holes

Super Giant stars make Black Holes. The gravity is very strong in these

enormous stars, and it keeps pushing and condensing the gases and matter

(stuff).

Black Holes

Eventually it will get smaller than an atom. All of the stuff from a star, smaller than

an atom!!

Black Holes

The gravity of black holes is so strong that nothing can get away from it.

Not even light!

We don’t know what a Black Hole looks like, because we

can’t see them!!