Many Planets Could Circle Twin Suns, NASA Says

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So Trilling's team used Spitzer's infrared cameras to scan for planetary disks instead.

"Spitzer is very good at detecting emitted thermal radiation from dust," Trilling said. "When we're searching for the dust disks, we're looking at a wavelength at which the stars are faint but the dust is bright."

Of the 69 binary systems the team studied, 40 percent were shown to have these dusty disks, meaning they could very well have planets in orbit.

Tatooine Plausible

Astronomers had previously found that planetary disks exist in binary systems where the twin stars are very far apart from each other—about a hundred times farther apart than the distance between Earth and the sun.

Nearly 200 planets outside our solar system have been discovered so far with the wobble technique. About a quarter orbit one star in a binary system (related: "Many 'Earths' Are Out There, Study Says" [April 6, 2005]).

The latest project focused on binary stars that are much closer together—less than 500 times the distance between Earth and the sun.

What really astonished astronomers was that 60 percent of the tightly circling twin stars they saw had dusty disks—a setup that could create a scene like the Tatooine sunset in Star Wars.

This finding actually makes perfect sense, said Alan P. Boss, an expert in planet formation at the Carnegie Institution in Washington, D.C.

"The close binary appears to be pretty much a single, massive star to the material in orbit around it that is trying to form a planetary system," Boss said in an email interview.

And "if the planetary orbits are stable and at a distance where liquid water is possible, then they will be habitable."

If planets are in the dusty disks spied by Spitzer, there's no reason some of them couldn't support life, study author Trilling said.

"I've been thinking about it, and there's nothing astronomically wrong with that picture," he noted, referring to the famous movie still (see photo above).

"But it is still science fiction—there's no reason to believe it really exists."

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