Download 3 rd stage of a star`s life = red giant

STARS
Life Cycle of A Star
1. Stars begin their lives as clouds of dust and
gas called a stellar nebula.
How A Protostar Is Formed
The gravity of a passing star or the shock wave from a
nearby supernova may cause the nebula to contract.
1. Matter in the gas cloud will begin to come together into
a dense region called a protostar.
2. As the protostar continues to condense, it heats up.
3. Eventually, it reaches a critical mass and nuclear fusion
begins.
4. This begins the main sequence phase of the star. Our
Sun is a main sequence star.
PROTOSTAR
Main Sequence Stars
1. The life span of a star depends on its size.
2. Very massive stars will become blue giants
during their main sequence.
Their main sequence may last only a few hundred
thousand years.
3. Smaller stars, like the Sun, will burn for several
billion years during their main sequence stage.
4. Our Sun is in its main sequence.
Main Sequence

After a star forms, it enters its 2nd & longest part of its life—
main sequence

Hydrogen fuses together to make helium, releasing large
amounts of energy—much in the form of heat & light.

Stars that lose their gas slowly stay on the main sequence a
long time.

Stars that lose their gas quickly stay on the main sequence a
short time.
The main sequence is the longest part of a star’s life
Average sized
star like our
Sun during
main sequence.
Massive star larger
than our Sun during
main sequence
3rd stage of a star’s life = red giant
 Goes
to this after leaving the main
sequence because it has used most of its
hydrogen
 The
star continues to cool after leaving
the main sequence, forming a red giant
(10X sun) or red supergiant (10 to 100X
the sun)
Red Giant and Red Supergiant
1. Eventually, the star's fuel will begin to run
out.
2. Our Sun will expand into what is known
as a red giant.
3. Massive stars will become red
supergiants.
4. This phase will last until the star exhausts
its remaining fuel.
5. At this point, the star will collapse.
Planetary Nebula
Most average stars will blow away their outer
atmospheres to form a planetary nebula.
Shells of gas thrown out by some stars near
the end of their lives
Planetary Nebula
White Dwarfs

Final stage of a star’s life cycle

Small, hot star made from the leftover core
of a star

Can shine for billions of years before
cooling completely
White Dwarf
 Their
cores will remain behind and
burn as a white dwarf until they cool
down.
 From a planetary nebula an average
star will become one of these,
radiating into space
When Average Stars die

Average stars becomes red giants & then
white dwarfs (stars like our sun)
White Dwarf
Dark Dwarf
What will be left is a dark ball of matter
known as a black dwarf.
The last phase of an average star’s life
Life Cycle of our Sun
1.
2.
3.
4.
5.
6.
7.
Stellar Nebula
Protostar
Main Sequence
Red Giant
Planetary Nebula
White Dwarf
Black Dwarf
Massive Stars
1. If the star is massive enough, the collapse will
trigger a violent explosion known as a
supernova.
2. If the remaining mass of the star is about 1.4
times that of our Sun, it will collapse further to
become a neutron star.
3. If the remaining mass of the star is more than
about three times that of the Sun, it will collapse
and what is left behind is an intense region of
gravity called a black hole.
Massive Stars (Larger than our Sun)
Become Red Supergiants.
Red Supergiant becomes Supernova
in a giant explosion,
OR It becomes a Black Hole
This is an illustration, not an actual
black hole!!
Supernova Becomes a Neutron Star
Life Cycle of a Massive Star
Stellar Nebula
2. Protostar
3. Blue Giant
4. Red Supergiant
5. Supernova
6. Neutron Star
(Pulsar)
OR
7. Black Hole
1.
Interactive Website
• http://aspire.cosmicray.org/labs/star_life/starlife_main.html