Birth of an Earthlike Planet Spied By Spitzer

October 3, 2007

A warm belt of dust around a young star is offering astronomers a glimpse of what Earth might have looked like when it was just beginning to take shape.

The star is part of a binary system known as HD 113766 that lies 424 light-years away.

Although it is slightly more massive than our sun, the star is only about 16 million years old—a baby compared to our 4.6-billion-year-old solar system.

And this young star seems to be in the early stages of forming its own rocky planets, a new study suggests.

The star system HD 113766 stands out clearly when looked at in infrared light, the part of the spectrum where dust shows up best.

Based on infrared data from NASA's Spitzer Space Telescope, astronomers say that the dust seems to be collected in a ring around the star within its "habitable zone," the region where water can stay liquid (see images from Spitzer).

Although the researchers can't see if any larger rocks have taken shape inside the dust, the abundance of material suggests that there's enough to form at least a Mars-size planet—or perhaps an Earth-size one.

"You've got all the right kinds of stuff—the age, the mass, the right location," said Carey Lisse of Johns Hopkins University in Maryland.

Lisse and colleagues will present their findings in an upcoming issue of the Astrophysical Journal.

Dust in Infrared

By examining the composition of the warm dust disk, Lisse's team was able to pinpoint what sort of body is most likely forming around the star.

A special instrument aboard Spitzer can search in the infrared spectrum for the fingerprints of particular molecules in the distant dust.

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