Origin of Milky Way Clouds Revealed
Mysterious clouds of gas hovering above the plane of the Milky Way may be the fractured remnants of superbubbles blown by stellar winds and exploding stars.
“There’s a fundamental, interesting connection between gas far away from the Milky Way and the amount of star formation below it in the galactic plane,” F. Jay Lockman of the National Radio Astronomy Observatory told Wired Science in a phone interview. The results could provide insight into how heavy elements traverse the galaxy and get incorporated into later generations of stars, planets and, perhaps, life.
The bulk of the matter in the Milky Way, including stars, hot star-forming regions and the gas and dust between stars called the interstellar medium, lies in a relatively flat disk called the galactic plane.
“It’s a flattened system, kind of like a pierogi,” Lockman said today at the American Astronomical Society in Miami.
The Milky Way also has a gaseous halo that extends above and below the galactic pastry. For years, astronomers expected the density of that gas to get thinner as it got farther from the Milky Way, the way Earth’s atmosphere thins out at high altitudes. But earlier observations Lockman made at the Green Bank Telescope in West Virginia showed dense clouds hundreds of times more massive than the sun floating between the disk and the halo, hundreds to thousands of light-years above the galactic plane.
“This turned my whole conception of what was going on upside down,” he said. “It’s very much like seeing, all your life, a distant hillside that’s covered in green fuzz. Then one day you get a pair of binoculars and you look and say, ‘My God, there’s trees!’”
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http://www.wired.com/wiredscience/2010/05/milky-way-clouds/#ixzz0p4derBQa
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