4.2 Stars have Life Cycles


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Presented on Monday November 23rd. This follows the textbook- Chapter 4 Section 4.3

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4.2 Stars have Life Cycles

  1. 1. Stars changed over their life cycles<br />Space Science:<br />Chapter 4: Section 4.2<br />
  2. 2. Let’s Begin<br />Why do stars look like small points of light?<br />Why don’t they look like in the sky?<br />Stars are very far away.<br />We only see a few thousand of stars that exist.<br />
  3. 3. What unit of measurement do we use to measure the distance between stars?<br />Light-years<br />The distance light travels in one year<br />Approximately 6 trillion miles<br />The closest star to Earth is our Sun<br />The next closest star is 4 light years away<br />
  4. 4. How do we measure how far stars are away from Earth?<br />Using parallax<br />The apparent shift in the position of an object when viewed from different locations<br />Parallax Demonstrations<br />
  5. 5. Size: the Sun’s diameter is 100x greater than Earth’s <br />
  6. 6. Some stars are much larger than the Sun. Giant and Super giants are 10-100’s of times larger.<br />
  7. 7. Betelgeuse: <br />600 times greater than the Sun<br />
  8. 8. There are stars much smaller than the Sun as well. These are called white dwarfs. <br />
  9. 9. What color are the stars we see?<br />Most stars are white<br />Some appear red<br />Some appear blue<br />Why is that?<br />Differences in color are due to differences in temperature<br />
  10. 10. Think of:<br />The metal coils inside of a toaster<br />Start off as a dull red<br />Later turn a bright orange<br />Temperature affects color by heating up the metal<br />
  11. 11. Stars have life cycles:<br />Length of the cycle and the way a star changes depends on the mass of the star<br />
  12. 12. Nebula:<br />All stars form inside a cloud of gas and dust called a nebula<br />Gravity pulls the dust closer together<br />The matter contracts and forms a hot dense sphere<br />
  13. 13. Main Sequence:<br />Fusion begins if the matter gains enough temperature and density<br />The birth of main sequencestars<br />
  14. 14. Low-Mass Stars:<br />Once fusion begins the star is then classified as a main sequence star<br />Low-mass stars use their fuel slowly<br />Remain in this stage for billions of years<br />As low-mass stars run out of fuel it expands into a giant star<br />Once the giant sheds it outer layer it leaves behind a dead core called a white dwarf<br />
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  16. 16. High-Mass Stars:<br />Once fusion begins the star is then classified as a main sequence star<br />High-mass stars use their fuel quickly<br />Remain in this stage for millions of years<br />As high- mass stars run out of fuel it expands into a super giant <br />The super giant explodes when no more fusion can occur- called a supernova<br />
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  18. 18. High-Mass Stars: After supernova<br />May form a dense body called a neutron star<br />Star squeezes itself smaller<br />Very DENSE- Example: pea size sample weighs 100 million tons<br />Gravitational force collapses atoms<br />Electrons combined with protons to produce neutrons<br />May form a black hole<br />More dense than neutron star<br />Intense surface gravity lets no light escape<br />As matter is pulled into the black hole it becomes very hot and emits x-rays<br />
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  20. 20. The Sun is what type of star?<br />Low-Mass<br />Main Sequence Star<br />What is going to happen to the Sun?<br />Eventually expand into a Red Giant<br />Cool down into a white dwarf<br />Scientist predict that in 4.5 billions years the Sun will run out of fuel and will form a Red Giant<br />