CHICAGO -- The halo of stars that envelops the Milky Way galaxy is like a river delta criss-crossed by stellar streams large and small, according to new data from the Sloan Digital Sky Survey (SDSS-II). While the largest rivers of this delta have been mapped out over the last decade, analysis of the new SDSS-II map shows that smaller streams can be found throughout the stellar halo, said Kevin Schlaufman, a graduate student at the University of California at Santa Cruz.
A theoretical model of a galaxy like the Milky Way, showing trails of stars torn from disrupted satellite galaxies that have merged with the central galaxy. The structures seen in the SDSS-II star maps support this prediction of a complicated outer Galaxy. The region shown is about one million light years on a side; the sun is just 25,000 light years from the center of the Galaxy and would appear close to the center of this picture. Credit: K. Johnston, J. Bullock
Schlaufman reported his results at an international symposium in Chicago, titled "The Sloan Digital Sky Survey: Asteroids to Cosmology." Over the last three years, Schlaufmann explained, the SEGUE survey of SDSS-II has measured the motions of nearly a quarter million stars in selected areas of the sky. A careful search for groups of stars at the same velocity turned up 14 distinct structures, 11 of them previously unknown.
Read the full story at: spaceflightnow.com
No comments:
Post a Comment