Birth and Death of Stars

Mrs. Brickley

6th Grade

ELES Battle Mountain, NV

What?

You mean stars are born and die, just like us?

Yup!

Everything does.

Stars are just stars……

Right?

You mean there are different kinds?

Sure!

How many ?

There’s a bunch.

Let’s see……there’s

Protostars

Medium-Sized Stars

White DwarfsMassive StarsSupernovas

Neutron Stars

Red Giant Stars

……and that’s not even talking about those

And our own

Let’s take a journey into space …..

and meet some of these guys.

ProtostarsGravity pulls huge nebulas of hydrogen gas and dust into a single spinning cloud.

Fusion begins…..

The mass begins to shine brightly.

A star is born!

As the particles crash into each other, the matter heats up….about 15 million degrees.

Here is a nebula.

……and a protostar is born.

What happens next?

That depends on the star’s mass in the beginning.

Medium-Sized Stars

Hydrogen fuel is fused into helium at the star’score until the hydrogen is used up.

The core shrinks, heats up, & releases energy.

The energy causes the star’s outer layers to expand, cool and become redder.

The core heats up and releases energy.

The star heats, expands, reddens and becomes a ……

Red Giant

The helium core continues to heat.

At ~ 200 million degrees the helium atoms fuse to form carbon atoms and the last of the hydrogen gases drift away.

These drifting gases form a nebula ring around the star.

The star is dying. It grows fainter andfainter.

Gravity causes its matter to collapseinward.

The star is squeezed into a……

White Dwarf

What are they?

They are superdense stars with carbon cores.

Since all of the mass of a star the size of our sun has been squeezed into the size of the earth,

all of the atoms are crowded together.

A chunk of the white dwarf the size of a sugar cube

They are so packed together…..

When the white dwarf’s energy is gone,

it becomes a dead star.

Would equal the mass of a CAR!

This is a white dwarf with a nebula cloud around it.

How long will a star live?

Our sun, a medium sized star, will liveabout 10 billion years.

Small stars will live about 100 billion years.

Large stars will only live a few billion years..

Massive Stars

……begin with about 6 times as much mass as our sun.

Like medium sized stars:

They burn hydrogen at first.

They redden as their helium core forms.

But, instead of becoming red giants …. they become supergiants.

As their cores heat up,

they fuse from helium….

to carbon…..

to oxygen and nitrogen….

to iron.

Then the fusion stops.

They expand into supergiants.

What happens next?

When the fuel runs out, gravity collapses the core even more.

The iron core absorbs energy instead of releasing it….

The star breaks apart in a terrific

The entire sky is lit up for weeks.

The temperature can be more than 100 billion degrees.

The iron atoms fuse into uranium.

The uranium and gases explode into space.

A gigantic cloud of gas and dust is left and may become a new nebula.

A Supernova!

New stars, like our earth, form from these remains.

This supernova is surrounded by a nebula ring.

Neutron StarsAfter the supernova explosion of a star 6-30 times the mass of the sun, a neutron star remains.

How big is it?

a chunk the size of a sugar cube

It’s only about 16Km in diameter,

but it has so much mass packed into it,

has the mass of ~ 100 MILLION CARS!!!

Stars 30 or more times the mass of our sun liveeven shorter lives and face a strange fate……

it is swallowed up by its own gravity.

After the supernova explosion,

the star’s core is so massive,

The core’s gravity is so strong that even light can’t escape.

The core has become a…..

Black Hole

The gravity from this black holeis pulling this matter into itself.

Black holes are like invisible cosmic vacuum cleaners.

They swallow both matter and energy.

How can we find them if we can’t see them?

Matter falling into a black hole releases large bursts of X-rays.

We can’t, for sure.

We can detect these.

What happens to this matter?

The laws of science may be different in a black hole.

We don’t know.

It’s probably squeezed out of existence,

just like the star that became the black hole.

How was the universe born?

No one knows for sure.

Some scientists have a theory.

Big Bang!They call it the

These astronomers believe 18-20 billion years ago all of the matter in the universe was packed into a very dense, very hot spot smaller than a dot!

all of them started racing away from each other.

It exploded.

Galaxies were formed,

We don’t know.

Will its gravity start pulling it back together?

We don’t know.

Will it keep expanding?

The universe is still expanding.

What DO we know?

We know the stars put on a super show every evening. All we have to do is stop and look upat the sky to enjoy it.

Now, let’s do a quick review.

Medium-Sized Stars

Protostar Sun

White Dwarf

Black Dwarf(dead star)

Red Giant

Supernova

Nebula

Red Supergiant

Neutron Star

High Mass

Very High M

ass

Black Hole

Supernova

Protostar

Massive Stars

Nebula

That’s all folks!