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← Measuring Starquakes

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Zeige Revision 4 erzeugt am 02/14/2019 von Karine Gantin.

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  2. You only know a planet as well as
    you know the star that it orbits.
  3. With Kepler, we have more than
    5,000 exoplanet detections.
  4. On top of that, it's made
    our understanding of stars
  5. far, far more advanced
    than it was six years ago.
  6. But it just so happens
    that the properties
  7. that you need from a spacecraft
    to be good at finding planets
  8. are also exactly the properties you need
  9. to be good at studying stars
    in certain ways.
  10. And the feature of Kepler
  11. that makes it great for
    stellar astronomy is the fact
  12. that it can measure the brightnesses
    of stars very precisely.
  13. That's the way you find planets,
  14. that's also the way you can see
    starquakes going on
  15. on the surfaces of stars.
  16. And those starquakes tell us
    about the masses of the stars themselves.
  17. We're typically familiar with earthquakes
  18. that are caused by
    tectonic plates shifting around,
  19. but the Earth actually quakes
    in a different way as well.
  20. It is constantly vibrating,
    and oscillating
  21. in much the same way that a bell would.
  22. It's oscillating at its resonant frequency,
    and that's an earthquake.
  23. Stars are similar to planets,
    they are more rarefied,
  24. they're made of sort of more
    of a fluid than a solid,
  25. but they still oscillate
    like the Earth does.
  26. Bells ring all the time
    through air particles,
  27. exciting their resonant frequency.
  28. Stars are exactly the same,
    they ring all the time.
  29. And just like a big bell has a deep ring,
  30. and a little bell has a high ring,
  31. stars are the same.
  32. So, if a star has a deep ring,
    it's massive,
  33. if it has a high ring, it's less massive.
  34. So, Kepler is really good at
    measuring masses of stars
  35. because it can see the stars ringing.
  36. And that's because it can measure
    the very precise brightness changes.
  37. Both in planets and in stars,
  38. Kepler has completely changed the field
  39. and revolutionized astronomy completely.
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