The star, called Beta Pictoris, is about 60 light-years away. Previous observations had shown a huge disk of dust and gas surrounding the star, a situation similar to the early years of our solar system. Beta Pictoris is thought to be just 20 million years old, whereas our Sun is now some 4.6 billion years old.

Researchers have previously found other evidence indicating that planets may be forming around Beta Pictoris.

The new study, done by an international team of astronomers using NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) spacecraft, shows how the chemistry of the disk implies that comets have formed. It also provides evidence that these comets are evaporating by the millions, say the scientists involved in the study.

A paper discussing the work appears in the Aug. 16 issue of the journal Nature.

"We are very excited about these observations because they are a rare glimpse at the chaotic birth of a solar system," said Dr. George Sonneborn, FUSE Project Scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

In the disk around the star, the research team found no evidence of molecular hydrogen, the most abundant molecule in the universe. But in earlier work, the same team found significant amounts of carbon monoxide. They expected just the opposite, based on the general knowledge of disks that have been found around other stars.

Stars tend to destroy carbon monoxide, and it is typically broken apart and virtually gone from the free space surrounding a star within about 1,000 years of the star's birth. So the scientists figure that carbon monoxide is somehow being stored in the Beta Pictoris disk and being released slowly, so that the supply is constantly replenished.

"Add this to the fact that the amount of molecular hydrogen is too low to be seen by FUSE," said Alain Lecavelier des Etangs of the Institut d'Astrophysique de Paris-CNRS. "This is strange because normally there are about 100,000 molecular hydrogen molecules for every carbon monoxide molecule in interstellar gas clouds. So we think the molecular hydrogen has been locked away in some kind of reservoir also."

Comets are a likely reservoir, the researchers said.

"In our own solar system, there is a swarm of thousands, perhaps millions, of comets beyond the orbit of Pluto," explained Paul Feldman of Johns Hopkins University, which operates FUSE. "If a similar comet swarm surrounds Beta Pictoris, the comets would still be warm enough to slowly release carbon monoxide, but far too cold to release molecular hydrogen, which would remain locked up as water ice."

In a separate recent study, researchers found vast quantities of water vapor circling an aging, massive star, a cloud they figure comes from a melting belt of icy comets that could be remnants of a distant planetary system there.

And the first evidence for an asteroid belt orbiting another star was announced in June of this year.

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