Birth and Death of Stars

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Birth and Death of Stars

• Mrs. Brickley
• 6th Grade
• ELES Battle Mountain, NV

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What?
You mean stars are born and die, just like us?
Yup!
Everything does.
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Stars are just stars
Right?
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Wrong!
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You mean there are different kinds?
Sure!
How many ?
bunch.
Theres a
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Lets seetheres
Protostars
Medium-Sized Stars
Red Giant Stars
White Dwarfs
Massive Stars
Supernovas
Neutron Stars
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and thats not even talking about those
mysterious
black holes
Universe.
And our own
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Lets take a journey into space ..
and meet some of these guys.
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Protostars
Gravity pulls huge nebulas of hydrogen gas and
dust into a single spinning cloud.
As the particles crash into each other, the
matter heats up.about 15 million degrees.
Fusion begins..
The mass begins to shine brightly.
A star is born!
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Here is a nebula.
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and a protostar is born.
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What happens next?
That depends on the stars mass in the
beginning.
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Medium-Sized Stars
Hydrogen fuel is fused into helium at the
stars core until the hydrogen is used up.
The core shrinks, heats up, releases energy.
The energy causes the stars outer layers to
expand, cool and become redder.
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The core heats up and releases energy.
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The star heats, expands, reddens and becomes a
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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.
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These drifting gases form a nebula ring around
the star.
The star is dying. It grows fainter and fainter.

Gravity causes its matter to collapse inward.
The star is squeezed into a
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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.
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They are so packed together..
A chunk of the white dwarf the size of a sugar
cube
Would equal the mass of a CAR!
When the white dwarfs energy is gone,
it becomes a dead star.
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This is a white dwarf with a nebula cloud around
it.
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How long will a star live?
Our sun, a medium sized star, will live about 10
billion years.
Small stars will live about 100 billion years.
Large stars will only live a few billion years..
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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.

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As their cores heat up,
they fuse from helium.
to carbon..
to oxygen and nitrogen.
to iron.
Then the fusion stops.
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They expand into supergiants.
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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
explosion!
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A Supernova!
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.
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New stars, like our earth, form from these
remains.
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This supernova is surrounded by a nebula ring.
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Neutron Stars
After the supernova explosion of a star 6-30
times the mass of the sun, a neutron star
remains.
How big is it?
Its only about 16Km in diameter,
but it has so much mass packed into it,
a chunk the size of a sugar cube
has the mass of 100 MILLION CARS!!!
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Stars 30 or more times the mass of our sun
live even shorter lives and face a strange fate
After the supernova explosion,
the stars core is so massive,
it is swallowed up by its own gravity.
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The cores gravity is so strong that even light
cant escape.
The core has become a..
Black Hole
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The gravity from this black hole is pulling this
matter into itself.
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Black holes are like invisible cosmic vacuum
cleaners.
They swallow both matter and energy.
How can we find them if we cant see them?
We cant, for sure.
Matter falling into a black hole releases large
bursts of X-rays.
We can detect these.
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What happens to this matter?
We dont know.
Its probably squeezed out of existence,
just like the star that became the black hole.
The laws of science may be different in a black
hole.
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How was the universe born?
No one knows for sure.
Some scientists have a theory.
Big Bang!
They call it the
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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!
It exploded.
Galaxies were formed,
all of them started racing away from each other.
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The universe is still expanding.
Will it keep expanding?
We dont know.
Will its gravity start pulling it back together?
We dont know.
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What DO we know?
We know the stars put on a super show every
evening. All we have to do is stop and look
up at the sky to enjoy it.
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Now, lets do a quick review.
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Supernova
Protostar
Sun
Red Giant
Nebula
White Dwarf
Black Dwarf (dead star)
Medium-Sized Stars
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Neutron Star
Supernova
Protostar
Red Supergiant
High Mass
Nebula
Very High Mass
Black Hole
Massive Stars
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Thats all folks!