Astronomers Discover Star-Studded Galaxy Tail

"The gas in this galaxy is being blown back into a turbulent wake," said Janice Hester of the California Institute of Technology in Pasadena, lead author of a recent study published in the Astrophysical Journal Letters. "The gas is like sand caught up by a stiff wind. However, the particular type of gas that is needed to make stars is heavier, like pebbles, and can't be blown out of the galaxy. The new Galaxy Evolution Explorer observations are teaching us that this heavier, star-forming gas can form in the wake, possibly in swirling eddies of gas."

Collisions between galaxies are a fairly common occurrence in the universe. Our Milky Way galaxy will crash into the Andromeda galaxy in a few billion years. Galaxies tangle together, kicking gas and dust all around. Often the battered galaxies are left with tails of material stripped off during the violence.

The astronomers were able to find this tail with the help of the Galaxy Evolution Explorer. Clusters of massive, young stars speckle the tail, and these stars glow with ultraviolet light that the space telescope can see. The young stars tell scientists that a crucial ingredient for star formation - dense clouds of gas called molecular hydrogen - formed in the wake of this galaxy's plunge. This is the first time astronomers have found solid evidence that clouds of molecular hydrogen can form under the violent conditions present in a turbulent wake.