Nearby Star System Could Spawn Carbon-Rich Planets

June 7, 2006

An unexpectedly large amount of carbon—the basis of life as we know it—surrounds a young nearby star where astronomers believe rocky planets are forming, according to a new study.

Such an environment might spawn tar-covered, diamond-rich worlds and life-forms that consume oxygen-rich foods, one scientist speculates.

The carbon discovery challenges ideas about the planets forming around the star in question, Beta Pictoris. The star is 63 light-years away and about twice the size of our sun.

"This is different than we expected," said Aki Roberge, an astronomer at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Many astronomers believe the Beta Pictoris system is similar to our solar system when it was much younger and the planets, including Earth, were forming. Beta Pictoris is thought to be between 8 and 20 million years old. Our solar system is at least 4.54 billion years old, scientists say.

Some evidence suggests a giant gas planet like Jupiter has already formed in the dusty disk around Beta Pictoris. Scientists believe terrestrial planets—planets with land, such as Mercury, Venus, Earth, and Mars—are forming right now.

(National Geographic magazine photos: "Search for Other Earths.")

Unexplained Carbon

Until now it's been a mystery as to why Beta Pictoris is enveloped in a gaseous disk, Roberge says.

Astronomers believed the gas was primarily composed of metal elements such as iron and silicon, which should have been getting blown away by radiation streaming out from the star.

"We shouldn't see [the clouds] where they are," Roberge said. "But we see them calmly in the disk orbiting the star. All previous theoretical work couldn't solve this."

Astronomers came to believe a hidden mass of gas, perhaps hydrogen, slowed the clouds' outflow.

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