2 Jupiter-sized planets orbiting double suns discovered

Astronomers have discovered two new low-density planets called Kepler-34b and Kepler-35b orbiting a binary star system.

The planets, which are comparable in size to Jupiter but much less massive, are actually a pair of gravitationally bound stars that orbit each other.

While the existence of such bodies, called “circumbinary planets,” had long been predicted, they remained just a theory until the team, including Eric B. Ford, UF associate professor of astronomy and William F. Welsh, associate professor at San Diego State University, and lead author on the paper, discovered Kepler-16b in September 2011.

They dubbed Kepler-16b “Tatooine” because of its resemblance to the two-sun world depicted in the “Star Wars” film series.

“We have long believed these kinds of planets to be possible, but they have been very difficult to detect for various technical reasons,” Ford said.

“With the discoveries of Kepler-16b, 34b and 35b, the Kepler mission has shown that the galaxy abounds with millions of planets orbiting two stars.”

The planets were discovered by measuring the star light decrease as the planets pass in front of, or transit, either of the two stars.

Kepler also measures the star light decrease when one of the stars passes in front of the other. The mutual gravitational tugs of the stars and planets cause the times of the transits to deviate from a regular schedule, allowing astronomers to confirm the planet and measure its mass.

Compared to Jupiter, Kepler-34 is about 24 percent smaller in size, but has 78 percent less mass. It can complete a full orbit in 288 terrestrial days. Kepler-35 is about 26 percent smaller, has 88 percent less mass, and completes its orbit around the stars much faster" just 131 days.

The astronomers believe the planets are made primarily of hydrogen and too hot to sustain life.

The study has been recently published in online edition of the journal Nature.