Post by Chicago Astronomer - Astro Joe on Jan 11, 2006 18:50:22 GMT -6
Huge star cluster discovered in neighborhood of Milky Way
Wednesday, January 11, 2006
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University Park, Pa. -- A team of scientists from the Sloan Digital Sky Survey (SDSS), including a Penn State astrophysicist, has discovered a companion to the Milky Way galaxy that is so big it previously had been undetectable. The result is the topic of a press conference during the meeting of the American Astronomical Society now taking place in Washington, D.C.
The study, lead by Mario Juric of Princeton and Zeljko Ivezic of the University of Washington, found a collection of stars in the constellation Virgo that covers nearly 5,000 times the size of the full moon.
The star cluster is located only 30,000 light years from Earth," Schneider said. "This is the same distance from us as is the Galactic Center, although the cluster lies in a different direction from the center. It is likely that the cluster is the remnant of a small galaxy that has been captured and disrupted by the gravitational field of our galaxy."
The galaxy is a huge but very faint structure, containing hundreds of thousands of stars spread over an area area nearly 5,000 times the size of a full moon. Although the structure lies well within the confines of the Milky Way Galaxy, at an estimated distance of 30,000 light years from Earth, it does not follow any of Milky Way's three main components: a flattened disk of stars in which the sun resides, a bulge of stars at the center of the galaxy and an extended, roughly spherical, stellar halo. Instead, the discoverers believe that the most likely interpretation of the new structure is a dwarf galaxy that is merging into the Milky Way.
"Some of the stars in this Milky Way companion have been seen with telescopes for centuries,'' explained Princeton University graduate student Mario Juric, who is principal author of the journal article describing what may well be our closest galactic neighbor. "But because the galaxy is so close, its stars are spread over a huge swath of the sky, and they always used to be lost in the sea of more numerous Milky Way stars. This galaxy is so big, we couldn't see it before.''
The discovery was made possible by the unprecedented depth and photometric accuracy of the SDSS, which to date has imaged roughly one quarter of the northern sky.
Full story here: live.psu.edu/story/15415
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Our galaxy has been attacking quite a few of our neighbors.
Quite aggresive...needs a time out.
