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B Dark matter not found in globular clusters orbiting MilkyWay

  1. Nov 28, 2017 #1
    On the podcast “Skeptics Guide to the Universe”, host, Steven Novella mentioned that astronomers can tell the difference between globular clusters orbiting the Milky Way Galaxy and satellite galaxies by looking to see if there is the gravitational effects of dark matter. Why would this be? That there is no dark matter in GC’s orbiting MW but satellite galaxies do? And isn’t this a good clue as to what dark matter may be or at least eliminate some ideas? I was unable to find any further info online, and thought this might be the right place to learn more.
    Thank you
     
  2. jcsd
  3. Nov 28, 2017 #2
    Welcome to PF.

    'Dark matter' is a placeholder name for stuff which has mass like normal matter, but is not visible.
    That is, it does not interact with the electromagnetic field
    Enough dark matter though produces gravitational effects which have been observed.
    We don't know what it is, but it's being worked on experimentally.
    The wiki summary is OK.
    https://en.wikipedia.org/wiki/Dark_matter
     
    Last edited: Nov 28, 2017
  4. Nov 29, 2017 #3

    davenn

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    Hi there
    welcome to PF :smile:


    Sorry, but that's rubbish .... globulars and galaxies are very different looking visually ... you don't need to use any other exotic method to distinguish their difference, like that guy is suggesting

    regards
    Dave
     
    Last edited: Nov 29, 2017
  5. Nov 29, 2017 #4

    stefan r

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    That does not answer Gordon Potter IV's question the way I read it. Why do globular clusters lack dark matter?

    I'll add the further question, "how accurately can you measure the dark matter in a globular cluster?"
     
  6. Nov 30, 2017 #5

    davenn

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    That wasn't the Q

    this was .....

    he never stated
    that is YOUR statement
     
  7. Nov 30, 2017 #6

    davenn

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    how can you measure something, that is still hypothetical ... accurately or otherwise ?
     
  8. Nov 30, 2017 #7

    Vanadium 50

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    By measuring the total mass and subtracting the mass of the stars.
     
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