Stars are born from dense nebulas of gas and dust that collapse under gravity to form protostars. Protostars gain mass through fusion and become full fledged stars. Medium sized stars like our sun initially fuse hydrogen into helium, then expand into red giants as their cores shrink and heat up. Eventually their cores collapse to form white dwarfs. Massive stars burn through fuel much faster, ending as supernovae that expel material to form new nebulae. The most massive stars may collapse into neutron stars or black holes. Black holes have such strong gravity that not even light can escape, though they can be detected by the X-rays of material falling into them.

1. Birth and Death of Stars
Mrs. Brickley
6th Grade
ELES Battle Mountain, NV

2. What?
You mean stars are born and
die, just like us?
Yup!
Everything does.

3. Stars are just stars……
Right?

5. You mean there are different
kinds?
Sure!
How many ?
There’s a bunch.

6. Let’s see……there’s
Protostars
Medium-Sized Stars
White Dwarfs
Massive Stars
Supernovas
Neutron Stars
Red Giant Stars

7. ……and that’s not even
talking about those
And our own

8. Let’s take a journey into space …..
and meet some of these guys.

9. Protostars
Gravity 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.

10. Here is a nebula.

11. ……and a protostar is born.

12. What happens next?
That depends on the star’s mass
in the beginning.

13. 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.

14. The core heats up and releases energy.

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

16. 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.

17. 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……

18. 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.

19. 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!

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

21. 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..

22. 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.

23. As their cores heat up,
they fuse from helium….
to carbon…..
to oxygen and nitrogen….
to iron.
Then the fusion stops.

24. They expand into supergiants.

25. 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

27. 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!

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

31. This supernova is
surrounded by a nebula ring.

32. 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?
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!!!

34. Stars 30 or more times the mass of our sun live
even 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,

36. The core’s gravity is so strong that even light can’t
escape.
The core has become a…..
Black Hole

37. The gravity from this black hole
is pulling this matter into itself.

38. 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.

39. 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.

41. How was the universe born?
No one knows for sure.
Some scientists have a theory.
Big Bang!They call it the

42. 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,

44. 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.

45. 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.

46. Now, let’s do a quick review.

47. Medium-Sized Stars
Protostar Sun
White Dwarf
Black Dwarf
(dead star)
Red Giant
Supernova
Nebula

48. Red Supergiant
Neutron Star
H
igh
M
ass
Very
H
igh
M
ass
Black Hole
Supernova
Protostar
Massive Stars
Nebula

49. That’s all folks!