Space.com/ September 15, 2011, 2:35 PM

Double-sun "Star Wars" planet discovered

It's a real-life Tatooine. A spectacle made popular by the "Star Wars" saga -- a planet with two suns -- has now been confirmed in space for the first time, astronomers revealed.

Scientists using NASA's Kepler space telescope captured details of a giant planet in orbit around the pair of binary stars that make up the Kepler-16 system, which is about 200 light-years away.

"This discovery is stunning," said study co-author Alan Boss at the Carnegie Institute in Washington. "Once again, what used to be science fiction has turned into reality."

Cosmic Diary about Kepler-16

The planet, dubbed Kepler-16(AB)-b, passes in front of both stars in view of the satellite, regularly dimming their light. Each star also eclipses its companion as they orbit each other. Altogether, these motions allow scientists to precisely calculate the masses, radii and trajectories of all three bodies. [See an image and video of Tatooine planet Kepler 16b]

The newfound planet keeps a distance from its stars nearly three-quarters that of the distance between the Earth and the sun. It is somewhat like Saturn in size, although nearly 50 percent denser, suggesting it is richer in heavy elements.

"Kepler-16(AB)-b is not habitable as we know it," said study lead author Laurance Doyle , an astrophysicist at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, Calif. 

This alien world travels on a nearly circular 229-day orbit around its two parent stars, Kepler-16A and Kepler-16B, which are about 69 and 20 percent as massive as the sun, respectively. The stars keep  close to each other -- only a fifth of the distance between Earth and the sun on average, which is closer than Mercury gets to the sun -- completing an orbit around each other every 41 days, researchers added.

Worlds that orbit around two stars, known as circumbinary planets, had been hinted at before. Stars in pairs both orbit around a point in space called barycenter, and researchers at times saw these orbits were slightly off, suggesting the presence of a planet tugging at both stars. However, Kepler-16(AB)-b is the first planet that scientists have detected directly passing in front of, or transiting, its stars, temporarily dimming their light.

Since the movements of this world and its two stars are all virtually confined to the same plane, the researchers suggest they all formed from the same disk of dust and gas. Planets that were captured from other star systems might be expected to orbit at a range of angles.

"Now that we know how to detect circumbinary planets, I think we are going to find a lot more rapidly," Doyle told SPACE.com.

The scientists detailed their findings in the Sept. 16 issue of the journal Science.

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9 Comments Add a Comment
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s1011 says:
planet with two suns , it's amasing.
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Zann-Zel says:
I'm still waiting for them to discover Pern, so I can go see the Dragonriders! : )
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bajajohn1 says:
And the people who live there are called Circum-Binarians meaning they come in pairs or are schizophrenic.
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DETracy says:
What keeps the two suns from colliding with each other? Because of gravitation attraction they should try to combine. Is this solar system shaped like a double yoked egg?
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retiredgustav says:
Many years ago I saw an episode of the Twilight Zone where everyone was a twin and there were two of everything including two suns in the sky. Rod Sterling was just a little ahead of his time.
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rrnc5lmce replies:
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I would agree with you if Rod Serling wrote the story of that Twilight Zone episode. He was just the host of that series....unless he wrote an episode or two....I don't know....
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obicera1 says:
I bet we wasted taxpayer dollars on this drivel. The government forced me to pay taxes and then gave it to 'scientists' to play with their expensive toys. We don't need to have this knowledge anyway. How is this going to benefit me? I want my money back. Why doesn't anyone understand it is all about ME!!
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rixmix98 replies:
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Without your last statement, I would have thought you were serious. Glad to know you weren't.
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mjlewis6 says:
This article might be more complete were there data regarding the output of the suns and the likely effect of such impacting the planetary body. It is very clear there is a tremendous energy impact with a large planet and the expected outcome of that energy on a dense body is to burn off lighter gases.

There would be a ring in the same plane of rotation were it further out. It is 'too close' to maintain an atmosphere given its size and relatively close distance to the suns.
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