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Life Cycle of the Stars

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

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Life Cycle of the Stars

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  1. Life Cycle of the Stars

  2. Life Cycle of Stars Average (sun-like) Stars Massive Stars http://hea-www.cfa.harvard.edu/CHAMP/EDUCATION/PUBLIC/ICONS/life_cycles.jpg

  3. 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…

  4. http://www.nasa.gov/multimedia/imagegallery/image_feature_73.htmlhttp://www.nasa.gov/multimedia/imagegallery/image_feature_73.html http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20070212.html NEBULA ____________: A dense cloud of gas and dust; the birthplace of stars. Horesehead Nebula; 1500 light years distant

  5. Bubble Nebula

  6. Crab Nebula

  7. Eye (of God) Nebula

  8. 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. Electrostatic attraction GRAVITY PROTOSTAR

  9. 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.

  10. Eventually, the protostar reaches a critical mass and nuclear fusionoccurs. • Thus begins the main sequencephase of the star • Most of its life is in this phase

  11. When the temperature gets hot enough, _______________ begins and the _______ ____________ stage begins. FUSION MAIN SEQUENCE Nuclear Fusion: The process of taking atom centers (the nucleus) and fusing them together.

  12. http://www.cosmosportal.eu/cosmos/tr/node/56058 H-R diagramHertsprung-Russell

  13. Life Cycle of Stars Life 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...

  14. Life Cycle of Stars • 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 ...

  15. Life Cycle of Stars • Average stars will expand into what is known as a Red Giant • Massive stars will become Super Red Giants

  16. Life Cycle of Stars • 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.

  17. A Red Giant You Know Betelgeuse (520 light years from Earth)

  18. Life Cycle of Stars • After a star completely runs out of fuel, it collapses instantaneously creating temps at the core upwards of 100 billion degrees • What happens next depends on the size of the star….

  19. Life Cycle of Stars • Most average stars (<1.5x Sun’s mass) will blow away their outer atmospheres to form a planetary nebula (no relation to actual planets)

  20. 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 known as a black dwarf

  21. As the fuel runs out in a average sized star, _________ slows down. The star will shrink in size, becoming a _________ _______. fusion White Dwarf A white dwarf is a small, white-hot remnant. They can reach temperatures of 100,000 Kelvin. They are also very dense.

  22. Review: Small/Medium Stars1. nebula2. protostar3. main sequence4. red giant5. planetary nebula/white dwarf6. black dwarf

  23. What about those MASSIVE stars?Their path is similar for the first four stages…1. nebula2. protostar3. main sequence4. SUPER red giant

  24. 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 supernova What happens next depends on the size of the star…

  25. explosion 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 Discovered by 14 year old Catherine Moore, on Nov. 7 2008. 1987 Supernova Large Magellanic Cloud 160,000 light years away

  26. 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

  27. After a supernovae the remnant may form a __________________. NEUTRON STAR 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! One scientist explained this is like taking the entire red supergiant and smushing it into a sphere 10 miles in diameter! http://chandra.harvard.edu/photo/2004/rxj1242/index.html http://www2.ph.ed.ac.uk/nuclear/photo/

  28. 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

  29. Life Cycle of Stars • To put it bluntly, black holes will blow your mind.

  30. 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

  31. Event Horizon Accretion Disk Jet (not always present) Singularity (deep in center) Black Holes - Dissected

  32. Stellar Mass Black Hole Cygnus X-I (in Milky Way galaxy; 8100 light years from Earth)

  33. Supermassive Black Hole Andromeda (center of Anrdomeda galaxy; 2.5M light years from Earth)

  34. Review: Massive Stars1. nebula2. protostar3. main sequence4. super red giant5. supernova6. neutron star OR black hole

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