Milky Way Mapped in 3-D

Dec. 12, 2007 -- The largest-ever three-dimensional survey of the Milky Way has just been released, listing more than 200 million objects in our home galaxy. The digital survey is already leading to discoveries about where in the sky stars are being born, as well as the relative numbers of different sorts of stars -- the galactic stellar demographics, if you will.

All the information is expected to help astronomers better understand the evolution of stars of all sorts, including our own, and improve our understanding of the layout of the Milky Way.

The survey was accomplished with one telescope on La Palma Islands in the Canaries, which looked at the galaxy entirely by the red light given off by hydrogen atoms. The "hydrogen-alpha" emissions reveal not only where the hottest stars are, but the stunning clouds of gas out of which they are created.

"Hot stars light up in these emission lines," said astronomer Nicholas Walton of the Institute of Astronomy at the University of Cambridge in the U.K.

Hot stars generally include those being born as well as those dying and shrinking into white dwarfs, he explained. So the hydrogen survey is helping sort out the locations of the Milky Way's stellar nurseries and old-age homes.

The hydrogen survey differs from the better known Sloan Digital Sky Survey (SDSS) in that it concentrates on the Milky Way, Walton said. The SDSS, on the other hand, avoids the Milky Way and focuses on the larger structures in the universe in other bands of light.

"They are very complimentary surveys," Walton told Discovery News.