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On the bright side, planets with 2 suns are common

March 31, 2007|John Johnson Jr. | Times Staff Writer

We're still waiting for speeders and light sabers, not to mention personal Death Stars to terrorize neighbors whose dogs won't stop barking.

But "Star Wars" may have gotten one piece of space science exactly right. The double sun like the one Luke Skywalker saw in the skies above Tatooine appears to be a more common arrangement than our single-star solar system, according to a new survey by the Spitzer Space Telescope.

"There appears to be no bias against having planetary system formation in binary systems," said the study's leader, David Trilling, an astronomer at the University of Arizona in Tucson. "There could be countless planets out there with two or more suns."

The finding is reported in the April 1 issue of the Astrophysical Journal. Previously, astronomers had seen planets circling one member of a widely separated star pair. Of the 200 planets discovered around stars other than our sun, 50 or so fit that arrangement. But the Spitzer team wanted to know whether planetary systems could grow around two closely connected stars.

Because standard planet-hunting methods -- such as observing the gravitational wobble of a star caused by a planet orbiting it -- don't work on binary systems, the Spitzer team came up with a new technique: looking for what are called "debris disks."

These dusty clouds of asteroids, comets and space flotsam indicate that the process of building planets is underway.

The team looked for the disks in 69 binary systems 50 to 200 light-years from Earth. They found that about 40% had the disks, more than around a similar group of single stars.

"We were very surprised," Trilling said. "This could mean planet formation favors tight binaries over single stars."

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