Presentation: life of a star

1. By: Mar, Patricia and Hanna.
Life of Stars

2. How is a Star Born?
Gas Giant
Brown Dwarf
Star

3. Classification:
M
M
=

5. FUN FACT: Giant Molecular Clouds,
or Nebulae can span 100 to even 600
light years in diameter!
The Life Cycle of an Average Star – Birth:
• The life cycle of
an average star
begins with its
birth. They
develop from
giant molecular
clouds.
• Giant Molecular Clouds are big and cold
collections of gas and dust. When they collapse
on themselves, stars begin the birthing process.
They start out as protostars and turn into main
sequence stars.

6. The Life Cycle of an Average
Star – The Middle Years:
• The way a star generates heat and
light is pretty simple, through the
process of nuclear fusion.
• Nuclear fusion is mostly simply described
in one of the most famous equations of all
time; mass energy equivalence: E=mc2,
by Albert Einstein.
• Nuclear fusion is the process in which
hydrogen atoms turn into helium.

7. TheLife Cycle of an Average Star –
The Golden Years:
The Red Giant Phase:
As the star’s core contracts
and its outer layers expand,
its heat and light decreases.
The helium atoms in the
star’s core begin to fuse
together, releasing energy
again!
Planetary Nebula Phase:
Its outer layers keep
expanding. Eventually the
outer layers drift out to
space.
As the star loses its outer
layers, the star continues
to cool off and decrease in
size.
• When our Sun
begins this
process, we’ll
be toasted!

8. TheLife Cycle of an Average Star – The
Golden Years:
White Dwarf Phase:
The star is in the state of
radiating its remaining
heat for up to billions of
additional years.
Black Dwarf Phase:
At this stage in the life cycle of an average
star, it’s basically dead.
A star will remain in the Black Dwarf state
until forever.

9. MASSIVE STARS
• Larger than 8 solar masses.
• PHASES:
1. Main sequence phase.
2. Short supergiant phase.
3. Spectacular death via a supernova
explosion.
It’s
volume
is 5
billion
times
greater
tha the
Sun.

10. MASSIVE STARS
THE MAIN LIFE SEQUENCE
• The life span of stars depend on their size.
• Very massive stars will become blue giants during their main sequence
• Balance between gravitational inward forces (centripetal force) and the core nuclear outward
forces (pressure).
• Its hydrogen will only last for millions of years. BLUE GIANT
Smalle
r stars
live
billions
of
years.
Our
Sun is
in its
main
sequen
ce.

11. MASSIVE STARS
RED SUPERGIANT
• The star’s fuel will begin to run out.
• The massive star will become a red
supergiant.
• This phase will last until the hydrogen is
exhausted.
RED SUPERGIANT
Gravita
tional
inward
forces.
(hydro
gen)
Fusion
outwar
d
forces.
(helium
)

12. MASSIVE STARS
SPECTACULAR DEATH
• If massive enough
SUPERNOVA
If the remaining mass is
about 1.4 times that of our sun.
NEUTRON STAR
• If the remaining mass:
3 x Sun, it’ll collpase.
BLACK HOLE

13. BIBLIOGRAPHY
• http://astronomyisawesome.com/galaxies/life-cycle-of-an-
average-star/
• www.skyandtelescope.com
• http://www.universetoday.com/13507/what-is-the-biggest-
star-in-the-universe/
• http://study.com/academy/lesson/massive-star-definition-
facts-life-cycle.html#lesson
• http://slideplayer.com/slide/9391706/http://
• www.space.com/22180-neutron-stars.html