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miércoles, 10 de junio de 2009

Galactic "Skid Marks" Trace Cosmic Collisions

Galaxies on collision courses with one another fling out long tendrils of debris as they come together, new images have revealed.

Tracing these debris trails will allow astronomers to more accurately model the trajectories of interacting galaxies before their violent encounters.

Team member Jin Koda of Stony Brook University in New York State compared the debris to skid marks at a traffic-accident site.

"If we look at only the wreck of the cars, we cannot tell what really happened," Koda said today during a meeting of the American Astronomical Society in Pasadena, California.

"But if we find skid marks on the road, then we can trace back the history of the collision."

Known as the Antennae, the galactic smashup seen above is happening 65 million light-years away in the constellation Corvus.

Using the Subaru Telescope on Mauna Kea volcano in Hawaii, astronomers were able to capture the Antennae's skid marks in unprecedented detail (bottom left).

The images, which were altered to boost contrast, show that the Antennae's debris trail is unexpectedly large, crossing an area a few times bigger than the Milky Way galaxy.

In addition to the Antennae, Subaru recorded debris trails from 12 other well-known galactic collisions. (See Hubble pictures of oddly shaped colliding galaxies.)

Astronomers think such collisions are critical to galaxy formation and evolution. Each event also triggers flurries of star creation, or starbursts.

Colliding galaxies often merge to become single galaxies, and the largest galaxies in the universe are thought to be the result of repeat pileups.

In fact, the Milky Way is expected to merge with our closest galactic neighbor, Andromeda, in about five billion years. (Related: "Earth Likely to Relocate in Galactic Collision.")

—Ker Than in Pasadena, California

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