Asteroid Belt Discovered Around Our Sun's "Twin"

Brian Handwerk
for National Geographic News
April 21, 2005

NASA's orbiting Spitzer Space Telescope has found evidence of a massive asteroid belt around a "twin" of our own sun.

Kim Weaver, a Spitzer Space Telescope scientist, said the finding marks "the first time that scientists have found evidence for a massive asteroid belt around a mature, sunlike star."

"This region around the star is the sort of place where rocky planets [like Earth] may form," Weaver said yesterday at a press conference from NASA headquarters in Washington, D.C.

The star, dubbed HD69830, is some 41 light-years away—which, in space terms, is practically our own backyard. Part of the constellation Puppis, the star is a tad too faint to see with the unaided eye.

The discovery may help reveal how other Earth-like planets could be formed and whether our own solar system is common or unique in space.

Construction Site or Junkyard?

"Asteroids are the leftover building blocks of rocky planets like Earth," said Charles Beichman, a Spitzer Space Telescope scientist based at the California Institute of Technology in Pasadena.

Beichman is the lead author of a paper describing the new asteroid belt, which will be published in Astrophysical Journal.

"We're interested in asteroid belts in these systems," Beichman said, "because they may mark either the construction sites that accompany the formation of rocky planets, the junkyards that remain after the formation of such planets, or simply places where, for one reason or another, material just couldn't assemble to form planets at all. "

Asteroids occassionally collide with each other, raising cosmic dust. They also crash into planets and moons.

The new asteroid belt was signalled by a thick disk of small dust grains that star HD69830 warms to temperatures that range from room temperature to 450° Fahreinheit (232° Celsius).

Of the 85 stars Spitzer scientists have examined to date, only HD69830 yielded evidence of an asteroid belt. It is thicker than the asteroid belt in our own solar system, which lies between Mars and Jupiter and packs nearly 25 times more debris.

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