Upstream | November 22, 2009 | 10 comments

Dark galaxy crashing into Milky Way

source: http://www.newscientist.com/article/mg20427354.200-dark-galaxy-crashing-into-the-milky-way.html

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THE Milky Way's neighbourhood may be teeming with invisible galaxies, one of which appears to be crashing into our own.

In 2008, a cloud of hydrogen with a mass then estimated at about 1 million suns was found to be colliding with our galaxy. Now it appears the object is massive enough to be a galaxy itself.

Called Smith's cloud, it has managed to avoid disintegrating during its smash-up with our own, much bigger galaxy. What's more, its trajectory suggests it punched through the disc of our galaxy once before, about 70 million years ago.

To have survived, it must contain much more matter than previously thought, in order to provide enough gravity to hold it together. Calculations by Matthew Nichols and Joss Bland-Hawthorn of the University of Sydney, Australia, indicate that it has about 100 times the previously estimated mass.

Many more such dark galaxies may be out there, says Leo Blitz of the University of California, Berkeley. Simulations of galaxy formation suggest a galaxy the size of the Milky Way should feature about 1000 dwarf galaxies, but only a few dozen have been found so far. Some of the missing dwarfs may be dark galaxies that are all but invisible, he says.


http://www.newscientist.com/article/mg20427354.200-dark-galaxy-crashing-into-the...
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10 comments // Dark galaxy crashing into Milky Way

  • JETaylor
  • cynker
  • jubal
    • 0
      jubal  

    • Its really a shame that we can't see what is happening on the other side of our Galaxy that is directly behind the center from our point of view. For all we know, a much larger and more menacing galaxy or dark galaxy could be colliding with the center of ours without us even knowing it. The end could already be here and it would take light years for us to even realize that our galaxy has already come to an end.

    • 2 years ago
  • stuknda70s
  • cynker
  • ras_menelik
  • ras_menelik
  • ras_menelik
  • ras_menelik
    • 0
      ras_menelik  
    • Image

    • 70 million?!?

      65 million years ago a disaster happened, although we are not sure of the cause....

      small exchange between an alienation galaxy?

      From Wikipedia
      Smith's Cloud is a high velocity cloud of hydrogen gas located in the constellation Aquila at Galactic coordinates l = 39°, b = −13°. The cloud was discovered in 1963 by Gail Bieger, née Smith, who was an astronomy student at Leiden University in the Netherlands.[1][2] Smith's cloud has a mass of at least one million solar masses and measures 3,000 parsecs (9,800 ly) long by 1,000 pc (3,300 ly) wide in projection.[3] The cloud is between 11,100 pc (36,000 ly) and 13,700 pc (45,000 ly) from Earth[3] and has an angular diameter of 10 to 12 degrees, approximately as wide as the Orion constellation, or about 20 times the diameter of the full moon, although the cloud is not visible to the naked eye.[1]

      The cloud is apparently moving towards the disk of the Milky Way at 73 ± 26 kilometers per second. Smith's Cloud is expected to merge with the Milky Way in 27 million years at a point in the Perseus arm. Astronomers believe it will strike the Milky Way disk at a 45° angle, and its impact may produce a burst of star formation or a supershell of neutral hydrogen

    • 2 years ago
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