Post by Chicago Astronomer - Astro Joe on Mar 16, 2006 2:21:15 GMT -6
River Of Stars Flows Through Milky Way
Pasadena CA (SPX) Mar 15, 2006
Astronomers have discovered a narrow stream of stars extending at least 45 degrees across the northern sky. The stream is about 76,000 light-years distant from Earth and forms a giant arc over the disk of the Milky Way galaxy.
"We were blown away by just how long this thing is," said Carl Grillmair of the California Institute of Technology. Grillmair and Roberta Johnson, a graduate student at California State University Long Beach, reported the discovery in the March issue of the Astrophysical Journal Letters.
"As one end of the stream clears the horizon this evening, the other will already be halfway up the sky," Grillmair said.
The stream begins just south of the bowl of the Big Dipper and continues in an almost straight line to a point about 12 degrees east of the bright star Arcturus in the constellation Bootes. The stream emanates from a cluster of about 50,000 stars known as NGC 5466.
The newly discovered stream extends both ahead and behind NGC 5466 in its orbit around the galaxy, and is powered by a process called tidal stripping, resulting when the force of the Milky Way's gravity becomes markedly different on one side of the cluster compared to the other. This phenomenon tends to stretch the cluster, which normally is almost spherical, along a line pointing towards the galactic center.
At some point - particularly when its orbit takes it close to the galactic center - the cluster can no longer hang onto its most outlying stars, and these stars drift off into orbits of their own. The lost stars that find themselves between the cluster and the galactic center begin to move slowly ahead of the cluster in its orbit, while the stars that drift outward and away from the galactic center fall slowly behind.
Source here: www.spacedaily.com/reports/River_Of_Stars_Flows_Through_Milky_Way.html
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I'm sure, like ocean currents, there are galactic currents all over the place!... #wha#
