What effect is thought to be due to the presence of "dark matter" around spiral galaxies?

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    High star-formation rates occur in interacting galaxies.
     Jets of energy appear to shoot up along the rotational axes of large galaxies.
     The rotation rates of spiral galaxies and orbital interactions among galaxies within clusters suggests the presence of extra mass around them.
     All galaxies with positive redshifts appear to be losing material.
     Elliptical galaxies have no Cepheid variable stars.
asked Sep 20, 2012 in Astronomy by anonymous
    

1 Answer

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The rotation rates of spiral galaxies and orbital interactions among galaxies within clusters suggests the presence of extra mass around them.
answered Sep 22, 2012 by SkyStar ~Expert~ (2,855 points)



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