life cycle of the stars
DESCRIPTION
Life Cycle of the Stars. Life Cycle of Stars. Average (sun-like) Stars. Massive Stars. http://hea-www.cfa.harvard.edu/CHAMP/EDUCATION/PUBLIC/ICONS/life_cycles.jpg. Life Cycle of Stars. Begin their lives as clouds of dust and gas called nebulae Gravity causes the nebula to contract - PowerPoint PPT PresentationTRANSCRIPT
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Life Cycle of the Stars
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Life Cycle of Stars
http://hea-www.cfa.harvard.edu/CHAMP/EDUCATION/PUBLIC/ICONS/life_cycles.jpg
Average (sun-like) Stars Massive Stars
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Life Cycle of Stars• Begin their lives as clouds of dust and gas called
nebulae
• Gravity causes the nebula to contract
• Matter in the gas cloud will begin to condense into a dense region called a protostar
Here are a few examples of some sweet nebulas…
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Horesehead Nebula; 1500 light years distant
http://www.nasa.gov/multimedia/imagegallery/image_feature_73.htmlhttp://www.nasa.gov/mission_pages/spitzer/news/spitzer-20070212.html ____________:
A dense cloud of gas and dust; the birthplace of
stars.
NEBULA
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Bubble Nebula
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Crab Nebula
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Eye (of God) Nebula
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Particles in the nebula initially hit each other and stick due to
______________________.
Eventually, ____________ of particles pulls other particles in. The pressure and temperature increase
and a _____________ forms.
GRAVITY
PROTOSTAR
Electrostatic attraction
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• Matter in the gas cloud will begin to condense into a dense region called a protostar
• As the protostar continues to condense, it heats up.
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• Eventually, the protostar reaches a critical mass and nuclear fusion occurs.
• Thus begins the main sequence phase of the star
• Most of its life is in this phase
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When the temperature gets hot enough, _______________ begins and the _______ ____________ stage begins.
FUSIONMAIN SEQUENCE
Nuclear Fusion: The process
of taking atom centers (the nucleus) and fusing them together.
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H-R
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http://www.cosmosportal.eu/cosmos/tr/node/56058
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Life Cycle of StarsLife span of a star depends on its size.
– Very large, massive stars burn their fuel much faster than smaller stars
– Their main sequence may last only a few hundred thousand years
– Smaller stars (average, sun-like stars) will live on for billions of years because they burn their fuel much more slowly
Regardless, eventually the star's fuel will begin to run out...
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• After Hydrogen is exhausted in core ...– Energy released from nuclear fusion – Counter-acts inward force of gravity.
• Core collapses, – Kinetic energy of collapse converted into heat.– This heat expands the outer layers.
• Meanwhile, as core collapses, – Increasing temperature and pressure ...
Life Cycle of Stars
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Life Cycle of Stars• Average stars will expand into what is
known as a Red Giant
• Massive stars will become Super Red Giants
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• In the (Super) Red Giant stage:–After helium is exhausted, the outer layers of the star continue to expand, while the core contracts becoming denser and hot enough to fuse larger atoms:. • 12C + 12C --> 24Mg
or… 12C + 4H 16O
• Through a combination of processes, successively heavier elements are formed and burned.
Life Cycle of Stars
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A Red Giant You Know
Betelgeuse (520 light years from Earth)
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• After a star completely runs out of fuel, itcollapses instantaneously
creating temps at the core upwards of 100 billion degrees
• What happens next depends on the size of the star….
Life Cycle of Stars
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• Most average stars (<1.5x Sun’s mass) will blow away their outer atmospheres to form a planetary nebula(no relation to actual planets)
Life Cycle of Stars
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Life Cycle of Stars• Their cores will remain behind and burn as
a white dwarf until they cool down– Size of the Earth with mass of the Sun
• 1 tsp = +100 billion tons– Inward force of gravity balanced by repulsive
force of electrons.
• What will be left is a dark ball of matter knownas a black dwarf
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As the fuel runs out in a average sized star, _________ slows down. The star will shrink in size, becoming a _________ _______.
fusionWhite Dwarf
A white dwarf is a small, white-hot remnant. They can reach temperatures of 100,000 Kelvin. They are also very dense.
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Review: Small/Medium Stars
1. nebula2. protostar
3. main sequence4. red giant
5. planetary nebula/white dwarf6. black dwarf
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What about those MASSIVE stars?
Their path is similar for the first four stages…
1. nebula2. protostar
3. main sequence4. SUPER red giant
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Life Cycle of Stars• If the star is
massive enough(>1.5x sun’s mass)
the collapse will trigger a violent explosion known as a supernovaWhat happens next depends on the size of the star…
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A ___________________ is an _____________ 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.
SUPERNOVA explosion
1987 SupernovaLarge Magellanic Cloud160,000 light years away
Discovered by 14 year old Catherine Moore, on Nov. 7 2008.
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Life Cycle of Stars• If it is a Huge Star (1.5x < sun’s mass < 3x) the core
is unable to support itself and it will collapse further to become a neutron star
• In the time it takes you to blink, a neutron star has rotated three times
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After a supernovae the remnant may form a __________________.NEUTRON STAR
http://chandra.harvard.edu/photo/2004/rxj1242/index.html
A neutron star is the core of the star, only now it is made up almost entirely of neutrons. A teaspoon of this material could weigh 10 million tonnes!
http://www2.ph.ed.ac.uk/nuclear/photo/
One scientist explained this is like taking the entire red supergiant and smushing it into a sphere 10 miles in diameter!
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Life Cycle of Stars• If it is a Giant (massive) Star (>3x sun’s mass), it
will collapse so completely that it will literally disappear from the universe.
• What is left behind is an intense region of gravity called a black hole
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Life Cycle of Stars
• To put it bluntly,black holes willblow your mind.
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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
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Black Holes - Dissected
Jet(not always present)
Accretion Disk Event Horizon
Singularity(deep in center)
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Stellar Mass Black Hole
Cygnus X-I (in Milky Way galaxy; 8100 light years from Earth)
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Supermassive Black Hole
Andromeda (center of Anrdomeda galaxy; 2.5M light years from Earth)
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Review: Massive Stars
1. nebula2. protostar
3. main sequence4. super red giant
5. supernova6. neutron star OR black hole