Breakthrough in Space II: Nasa discovers first exoplanet in a binary sun system

Jun 2011
NASA's Kepler mission discovers a world orbiting two stars

"The existence of a world with a double sunset, as portrayed in the film Star Wars more than 30 years ago, is now scientific fact. NASA's Kepler mission has made the first unambiguous detection of a circumbinary planet -- a planet orbiting two stars -- 200 light-years from Earth.

Unlike Star Wars’ Tatooine, the planet is cold, gaseous and not thought to harbor life, but its discovery demonstrates the diversity of planets in our galaxy. Previous research has hinted at the existence of circumbinary planets, but clear confirmation proved elusive. Kepler detected such a planet, known as Kepler-16b, by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.

"This discovery confirms a new class of planetary systems that could harbor life," Kepler principal investigator William Borucki said. "Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now....

..."Most of what we know about the sizes of stars comes from such eclipsing binary systems, and most of what we know about the size of planets comes from transits," said Doyle, who also is the lead author and a Kepler participating scientist. "Kepler-16 combines the best of both worlds, with stellar eclipses and planetary transits in one system."

This discovery confirms that Kepler-16b is an inhospitable, cold world about the size of Saturn and thought to be made up of about half rock and half gas. The parent stars are smaller than our sun. One is 69 percent the mass of the sun and the other only 20 percent. Kepler-16b orbits around both stars every 229 days, similar to Venus’ 225-day orbit, but lies outside the system’s habitable zone, where liquid water could exist on the surface, because the stars are cooler than our sun.

Here is an artist's rendition of Kepler 16-b:

CNN is also reporting this today.

It should be noted that the vast majority of confirmed exoplanets are essentially in our neighborhood of the milky way galaxy, around 300 cubic light years, which looks like so:

Look at all those other spirals in our milky way galaxy and just imagine for yourself how many millions of exoplanets there probably are alone in just our half of the galaxy. It is mind-boggling.

Here is another EXCELLENT Exoplanets website, with a graphical explorer and tables and all that great geeky numbers stuff.

This announcement came after announcement from ESO, which you will find in:

"Breakthrought in Space I: ESO discovers 50 new Exoplanets, one in the habitation zone"
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