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Thread: How does a galaxy die?

  1. #1 How does a galaxy die? 
    The Doctor Quantime's Avatar
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    Jun 2007
    I was just curious as to how a galaxy dies, (obviously ). Does the black hole in the centre have everything spiral towards it until everything is eaten up? Excuse the 'eaten', not very scientific I know :wink:.

    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan.
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  3. #2  
    Universal Mind John Galt's Avatar
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    Jul 2005
    It would die when all the GMCs have been converted to stars and all its stars have used up their fusion feedstock. There is nothing that would make the stars spiral into the black hole, so that won't happen.

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  4. #3  
    Forum Professor
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    Oct 2006
    svw; I agree, the likelihood a BH, under its current meaning could draw all the stars in a Galaxy, even reasonably near by, is impossible. Think the notion has developed by those feeling BH and the BBT singularity have something in common.

    As for Giant Molecular Clouds (GMC's) or there sisters, the smaller ones, its possible they form from debris to begin with and part of the Galaxy normal regeneration process. Our MW is said to have 1-2,000 such units and a good many of the smaller ones (less than 100,000 times our star mass).

    IMO and the way I read it, Galaxy do not simply die out. Most Galaxy are in fact Dwarfs, formed independently in Nebula or Gas Clouds and eventually become part of other galaxy. There are 20 or so such Dwarfs in orbit around our MW, a couple soon to be absorbed by the MW. Also we have Andromeda, which is thought will collide with our MW in about 5-6 Billion years. Our sun should be dieing by then, but for sure little earth should be long gone.

    A Galaxy can be torn apart however, under a couple said scenarios. NASA has some images of Abell 2667 Cluster, which they and other feels shows just such occurrence in one Galaxy. Its about 2.7 billion light years out there.
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  5. #4  
    Forum Ph.D. Wolf's Avatar
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    May 2007
    Depends on how you look at it. I'm not sure "galaxies" can ever really die in a physical sense, since they're essentially matter being moved around. If you regard the total sum of atoms as a galaxy, then the galaxy itself can only "die" if those atoms are dispersed, such as in a collision with another galaxy.

    Given the perpetual growth and decay of galaxies, it's more likely that a galaxy will be consumed (either directly or by dispersal) before the black holes at its center ever get a chance to collect all the material in the galaxy.
    "Be fair with others, but then keep after them until they're fair with you." Alan Alda
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