Dark Matter Could Explain Milky Ways Warp |
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Written by spacetravel.org
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Sunday, 15 January 2006 20:58 |
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Scientists have announced that a slow motion collision between dark matter and two of the Magellanic Clouds may be causing the Milky Way to warp.
The Milky Ways warp is most clearly visible in a thin disk of hydrogen gas that extends across the entire diameter of the Milky Way. Viewed sideways, one half of the hydrogen disk appears to stick up above the Milky Ways plane of stars and gas, while the other half dips below the plane for a bit and then rises upward again farther away from the galaxys centre.
For almost 50 years, astronomers have been wondering what causes the Milky Ways warp. An early explanation was that gravity from the Magellanic Clouds, two neighbouring dwarf galaxies, was causing the warp. However the explanation was dismissed after it was shown that the combined mass of the Magellanic Clouds is only about 2 percent of the Milky Ways hydrogen disk. This would not be enough to cause the warp.
However, researchers at the University of California, Berkeley have used a computer model to show that the Magellanic Clouds could warp the Milky Ways shape if they were moving through a thick halo of dark matter. The model shows that as the Magellanic Clouds interact with dark matter, they create vibrations that cause the Milky Ways hydrogen disk to oscillate. The researchers said the overall effect is like a tablecloth flapping in the wind. They believe similar processes may explain the shapes of other galaxies that are also warped.
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