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Re: This Week's Finds in Mathematical Physics (Week 224)

  1. Nov 4, 2006 #1
    Thus spake John Baez <baez@math.removethis.ucr.andthis.edu>
    >I checked and read there are 100 known "polar-ring galaxies". Here's a
    >nice one called NGC 4650:
    >
    >18) Ring around a galaxy, HubbleSite News Archive, May 6, 1999,
    >http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/16/imag
    >e/a
    >
    >I can imagine this thing looking like Hoag's object if we viewed it
    >head-on.
    >
    >Here's another ring galaxy, called AM 0644-741:
    >
    >19) The lure of the rings, Hubblesite News Archive, April 22, 2004,
    >http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/15/imag
    >e/a
    >
    >It's the result of a collision involving a galaxy that's not in this
    >picture. So, maybe Hoag's object is just a specially pretty case of a
    >galaxy collision!


    In spite of this one, which is not symmetrical, the explanation seems to
    imply that quite regularly a small galaxy has to pass bang through the
    middle and perpendicular to a large galaxy. Yes, it can happen, but
    surely not if there are loads of them. The thing that struck me about
    these things was that they seemed more like a galaxy which had had its
    middle blasted out by some massive explosion. Could they be the remnants
    of dead quasars? I know it sounds wrong, because the inner contains old
    stars, while the outer contains new ones, but we are seeing a lot of new
    stars forming at the outside of galaxies generally. If there is more
    matter in the outer ring, that is also where hydrogen will gather and
    stars will ignite?



    Regards

    --
    Charles Francis
    Please reply by name
     
  2. jcsd
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