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How Far nearby galaxy Problem

  1. May 4, 2005 #1
    A Cepheid variable in a nearby galaxy looks 10^6 times fainter than an identical Cepheid in the Milky Way. The Cepheid in the Milky Way is 1000 parsecs away. How far away is the nearby galaxy?

    I know this formula
    v = hd
    but how does that help me?
    i'm lost...
     
  2. jcsd
  3. May 4, 2005 #2

    SpaceTiger

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    It doesn't. Did you learn a formula for the dependence of brightness (flux) on distance?
     
  4. May 4, 2005 #3

    turbo

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    Here is a nice page that might be useful.

    http://staff.imsa.edu/science/astro/astrometry/rung4.html
     
  5. May 4, 2005 #4

    SpaceTiger

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  6. May 4, 2005 #5

    turbo

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    You're right, of course, but sometimes handing out the simplistic solution is not the best solution, like the old Chinese proverb:

    Give a man a fish and he will eat for a day. Teach a man to fish, and he will spend his weekends drinking beer and his weekdays lying about the one that got away.
     
  7. May 4, 2005 #6

    Chronos

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    This is really a very simple exercise. You need only know the luminosity distance relationship... or you could do it the way SpaceTiger suggested... :biggrin: [which is the same thing].
     
    Last edited: May 4, 2005
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