Transcript Star Cycle2013

Stars
A Star is an object that produces
energy at its core! A mass of
plasma held together by its own
gravity;
Energy is released as
electromagnetic radiation!
Stars differ in size, age and
temperature.
Star Power
Stars are powered by nuclear fusion
• At 15 million degrees Celsius in the center of the
star, fusion occurs.
• Very simplified:
4 Hydrogen  1 Helium + energy!
E=
2
mc
Nuclear fusion
• Fusion makes LOTS of energy
• E = mc2 What do E and M symbolize?
E = Energy and m = mass
….and “c”….?
c = the speed of light (300,000,000 m/s)
• Astronomers learn about stars by
studying their luminosity,
spectrum, and motion
Life Cycle
of
the Stars
Stars are formed, changed, and recycled!
Stars
• A celestial
body of hot
gases that
radiates
energy from
nuclear fusion
occurring at
the core.
Milky Way, Nebula NGC 3603
20,000 light years away
http://news.nationalgeographic.com/news/2007/10/images/071002-star-picture_big.jpg
_______
Light Year
_____ is the distance light can travel
in ONE YEAR. Light travels at a speed of
300,000,000 meters/second.
Milky Way, NGC 3949, 50 million light years
In one Second,
light can travel
around the Earth
10 times, according
to one estimate.
9,400,000,000,000,000 meters
9 quadrillion (9 thousand billion)
http://www.nasa.gov/multimedia/imagegallery/image_feature_202.html
http://www.nasa.gov/multimedia/imagegallery/image_feature_73.htm
l
http://www.nasa.gov/mission_pages/spitzer/news/spitzer20070212.html
____________:
NEBULA
A dense
cloud of gas
and dust; the
birthplace of
stars.
Horesehead Nebula; 1500 light years distant
Bubble Nebula
Stingray Nebula
Horsehead Nebula
Red Square Nebula
Crab Nebula
Eye (of God) Nebula
Southern Crab Nebula
Eskimo Nebula
The nebula begins to
contract due to __________.
GRAVITY
The pressure and
temperature increase as a
PROTOSTAR is formed.
_____________
When the temperature gets hot
FUSION
enough, _______________
begins
andMAIN
a _______
____________ star is
SEQUENCE
born.
Nuclear Fusion:
The process of
taking atom centers
( the nucleus) and
fusing them
together.
A Balancing Act
• Energy released from nuclear fusion
counter-acts inward force of gravity.
Throughout its life,
these two forces
determine the stages
of a star’s life.
MASS
A star loses ____________
during fusion as energy is
released.
This decreases the star’s
gravity. A star will expand,
becoming a
_______________.
RED GIANT
Very massive stars become
________
_____ GIANTS
_________.
SUPER RED
http://www.daviddarling.info/images/red_giant.gif
http://www.universetoday.com/2008/01/31/will-earth-survive-when-the-sun-becomes-a-red-giant/
As the fuel runs out in a average sized star,
fusion
_________
slows down. The star will shrink in
size, becoming a White
_________
_______.
Dwarf
PULSAR
A ____________
is a rotating white
dwarf emitting radio waves.
Small and medium stars cool and stop producing
energy. We then call them
___________________.
BLACK DWARVES
http://chandra.harvard.edu/photo/2004/rxj1242/index.html
http://www2.ph.ed.ac.uk/nuclear/photo/
A ___________________
SUPERNOVA
is an explosion
_____________ that marks the end of a very
massive star’s life.
When it occurs, the exploding
star can outshine all of the other stars in the galaxy in total
for several days and may leave behind only a crushed core.
Discovered by 14 year old Catherine Moore, on Nov. 7 2008.
1987 Supernova
Large Magellanic Cloud
160,000 light years away
Larger stars supernovae and form
__________________.
http://chandra.harvard.edu/photo/2004/rxj1242/index.html
http://www2.ph.ed.ac.uk/nuclear/photo/
The most massive stars supernovae and
form _________________
BLACK
HOLES
A black hole is an extremely massive
remnant from which light can not escape.
“Black holes are where God divided by zero”
Stephen Wright
The Largest stars are red supergiants,
1500 times our sun.
The smallest are red dwarfs, not much
larger than Jupiter.
What makes some stars appear
brighter?
• LUMINOSITY refers to the brightness of
stars. Because some stars are CLOSER
or BIGGER, they may seem more
luminous.
What makes some stars appear
different colors?
• The temperature affects the color. The
hottest stars are blue, while the coolest
stars are red.
Blue > 30,000 Kelvin
Blue to blue white 10,000 -> 30,000 Kelvin
White 7,500 -> 10,000 Kelvin
Yellowish White 6,000 -> 7,500 Kelvin
Yellow 5,200 -> 6,000 Kelvin
Orange 3,700 -> 5,200 Kelvin
Red 1,000 < 3,700 Kelvin
Brown < 1,000 Kelvin
Black 0 Kelvin
H-R diagram
http://www.cosmosportal.eu/cosmos/tr/node/56058
Do larger stars or smaller stars last
longer?
Do hot stars or cool stars last longer?
Large, more massive stars have much more
_____________
than the sun. This greater internal
gravity
pressure causes fusion reactions to occur
quickly
__________.
This causes the largest stars to burn
their fuel, and eventually run out, much more
______________.
quickly
Larger stars live ___________
lives.
shorter
Bigger stars are brighter and hotter due to the rapid
fusion
rate of __________.
All stars spend the majority of their lives
hydrogen
fusing __________
into helium
________________: the main sequence.
hydrogen in the central
When all of the _____________
regions is converted to helium, the star will begin
to “burn” helium into _______________.
carbon
Stars heavier than about 5 times the mass of the
______ can do this with no problem: they burn
hydrogen
helium
_____________,
and then _______________,
and
oxygen
carbon
then
_____________,
_______________, silicon, and
so on…until Iron.
Iron is the lightest element that doesn’t
energy when you attempt to
release __________
fuse it together. You actually end up with less
energy than you started with! So instead of
generating pressure to hold up the outer
layers, the iron fusion actually takes it out of
the core. Thus, there is nothing left to combat
gravity from the outer layers.
________________
supernova
The result: ___________!
Iron
collapse
This implosion (___________)
happens
very, very quickly: about 15 seconds.
During the collapse, the nuclei in the
outer parts of the star are pushed
together, so close that elements heavier
than __________
Iron
are formed.
Apparent Magnitude: How bright an
object appears from Earth.
Absolute Magnitude: How bright an
object would appear from 32.6 light years
away.
Low numbers are brighter. Negative
numbers are extremely bright.
The End.