Embargoed until 2p.m. (EST) November 24, 1999

A Puzzle of Galactic Evolution is Solved - Massive Gas Clouds Seed the Galaxy with the Stuff of Stars

Massive clouds of gas, discovered long ago but only recently identified as being within the margins of the Milky Way, play a key role in the ability of the galaxy to churn out new stars by raining gas onto the plane of the galaxy, a new report suggests. Writing this week in the scientific journal Nature, Bart P. Wakker, a University of Wisconsin-Madison astronomer, and colleagues have chipped away at a three-decade-old mystery about the nature and role of what astronomers call high-velocity clouds. In the process, they've discovered a mechanism by which the galaxy is seeded with the stuff of stars and solved a long-standing question of galactic evolution.

Photo Credits: Image composite by Ingrid Kallick of Possible Designs, Madison Wisconsin. The background Milky Way image is a drawing made at Lund Observatory. High-velocity clouds are from the survey done at Dwingeloo Observatory (Hulsbosch & Wakker, 1988).