Download File - Morgan, Kristen

There are lots of kinds of stars
Protostars
Medium-Sized Stars
Red Giant Stars
White Dwarfs
Massive Stars
Supernovas
Neutron Stars
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!
So 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’s
core 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 and
fainter.
Gravity causes its matter to collapse
inward.
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.
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 dwarf’s energy is
gone,
it becomes a dead star.
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..
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
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.
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?
It’s 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!!!
Stars 30 or more times the mass of our sun live
even shorter lives and face a strange fate……
After the supernova explosion,
the star’s core is so massive,
it is swallowed up by its own gravity.
The core’s gravity is so strong that even light can’t
escape.
The core has become a…..
Black Hole
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?
We can’t, for sure.
Matter falling into a black hole
releases large bursts of X-rays.
We can detect these.
What happens to this matter?
We don’t know.
It’s 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.
How was the universe born?
No one knows for sure.
Some scientists have a theory.
They call it the
Big Bang!
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.
The universe is still expanding.
Will it keep expanding?
We don’t know.
Will its gravity start pulling it back together?
We don’t know.
Supernova
Protostar
Nebula
Sun
Red Giant
White Dwarf
Black Dwarf
(dead star)
Medium-Sized Stars
Neutron Star
Protostar
Red Supergiant
Nebula
Black Hole
Massive Stars