Milky Way’s halo loaded with star streams

By Andrea Thompson, SPACE.com
A new map of the halo of stars that surrounds our Milky Way Galaxy has revealed a complicated structure of crisscrossing stellar streams, many of which have never been detected before.
While the bulk of our galaxy’s stars are concentrated in a fairly flat disk and a bulbous central region, the halo is the first thing an intergalactic traveler would encounter upon approaching our home galaxy. The halo begins at the edge of the disk around 65,000 light years from the galactic center and may extend out as far as 300,000 light years from the center of the galaxy. The halo comprises star clusters, clouds of gas, dark matter, and a few lone stars. Some of these pieces were grabbed up by the Milky Way from dwarf galaxies as they passed by.

The largest stellar streams in the halo have been mapped out over the last decade, but new data from the Sloan Digital Sky Survey (SDSS-II) has found many previously unknown smaller streams, remnants of dwarf galaxies that strayed too close and a few surviving companions.

The streams are remnants of smaller galaxies that have been consumed.

The new findings are being presented today at an international symposium in Chicago.

~ by lucidfaerie on August 20, 2008.