Life cycle of stars

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Notes from Mr. Olandese's DES class on the life cycle of stars.

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Life cycle of stars

  1. 1. Life Cycle of a Star
  2. 2. What are the stages of a star’s life? <ul><li>Depends on how they start their life!!!! </li></ul><ul><ul><ul><ul><li>High Mass </li></ul></ul></ul></ul><ul><ul><ul><ul><li>vs. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Low Mass </li></ul></ul></ul></ul>
  3. 3. What are the stages ? 1. Nebula 2a.Main Sequence 3a.Red Giant 4a.Planetary Nebula 5a. White Dwarf 6a.Black Dwarf 2b.Main Sequence 3b.Red Supergiant 4b.Supernova 5b.Neutron Star or 5b.Black Hole a: Low Mass Star b: High Mass Star
  4. 4. Compared to a Human Life Span Graphic Courtesy of: http://aspire.cosmic-ray.org/labs/star_life/starlife_main.html
  5. 6. What happens during the stages? <ul><li>Stage 1 – Nebula </li></ul><ul><ul><li>A cloud of dust and gas </li></ul></ul><ul><ul><li>When the gas and dust contracts under gravity, a protostar is born </li></ul></ul>
  6. 7. Stage 2 –Main Sequence <ul><li>Stage 2a </li></ul><ul><ul><li>Star reaches equilibrium (it’s stable) </li></ul></ul><ul><ul><li>Can last up to </li></ul></ul><ul><ul><li>10 billion years </li></ul></ul><ul><li>Stage 2b </li></ul><ul><ul><li>Can last less than </li></ul></ul><ul><ul><li>1 million years </li></ul></ul>
  7. 8. Stage 3a –Red Giant <ul><li>Hydrogen in core is depleted </li></ul><ul><li>Core contracts and heats up </li></ul><ul><li>Heat causes the outer layers to expand </li></ul><ul><li>Expanding causes the layers to cool </li></ul>
  8. 9. 4a –Planetary Nebula <ul><li>All helium in the giant has fused into carbon </li></ul><ul><li>Core collapses again </li></ul><ul><li>Outer layers of star are expelled into space </li></ul>
  9. 10. 5a –White Dwarf <ul><li>Core contracts even more </li></ul><ul><li>More layers expelled into space </li></ul><ul><li>Leaves behind only a hot, dense core (about the size of Earth) </li></ul>
  10. 11. 6a –Black Dwarf <ul><li>A non-radiating ball of gas where fusion has ceased. </li></ul>http://aspire.cosmic-ray.org/labs/star_life/hr_interactive.html -click on “Interactive Lab” graphic in the middle
  11. 13. Step 3b –Red Supergiant <ul><li>Hotter, larger and more orange than a red giant </li></ul>
  12. 14. 4b -Supernova <ul><li>All of the helium in a supergiant has fused into iron </li></ul><ul><li>The core collapses violently </li></ul><ul><li>The outer portion of the star explodes </li></ul><ul><li>Very Bright!!!! </li></ul>
  13. 15. 5b –Neutron Star <ul><li>If the core of a supernova has 2 times more mass than the sun; </li></ul><ul><ul><li>The core shrinks to 20 km in diameter </li></ul></ul><ul><ul><li>Only neutrons can exist there </li></ul></ul><ul><ul><li>1 tsp = 100 million tons </li></ul></ul>
  14. 16. 5b –Black Hole <ul><li>If the core of a supernova has 3 times more mass than the sun; </li></ul><ul><ul><li>Core collapses to the point that It has no volume </li></ul></ul><ul><ul><li>Gravity is so strong that nothing can escape, not even light </li></ul></ul>
  15. 17. How do the sizes of the stars compare?
  16. 19. <ul><li>Where are stars with the highest luminosity located? </li></ul><ul><li>Where are the stars with the highest temperature located? </li></ul><ul><li>Where are average stars located? </li></ul><ul><li>Where is our sun located and why? </li></ul>

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