jueves, 15 de septiembre de 2011

NASA Kepler finds planet orbiting two stars: Best example of a planet like Tatooine from Star Wars we've seen!

Kepler-16 planetary systemClick image for multiple resolutions and full caption.
Image: In the Light of Two Suns - This artist's concept illustrates Kepler-16b, the first planet known to definitively orbit two stars -- what's called a circumbinary planet. The planet, which can be seen in the foreground, was discovered by NASA's Kepler mission.
Image credit: NASA/JPL-Caltech/T. Pyle

Kepler-16 planetary systemClick image for multiple resolutions and full caption.
Image: Where the Sun Sets Twice - NASA's Kepler mission has discovered a world where two suns set over the horizon instead of just one. The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy. Tatooine is the name of Luke Skywalker's home world in the science fiction movieStar Wars. In this case, the planet it not thought to be habitable. It is a cold world, with a gaseous surface, but like Tatooine, it circles two stars.
Image credit: NASA/JPL-Caltech/R. Hurt

Three eclipsing bodiesClick image for video page with download capability and full caption.
Animation: Three Eclipsing Bodies - This artist's movie illustrates Kepler-16b, the first directly detected circumbinary planet, which is a planet that orbits two stars. The movie begins by showing the gaseous surface of the rotating planet then pans out to show the stars it orbits.
Image credit: NASA/JPL-Caltech/T. Pyle

A Dance of Two Suns and One PlanetClick image for video page with download capability and full caption.
Animation: A Dance of Two Suns and One Planet - This artist's animation illustrates the Kepler-16 system from an overhead view, showing the eccentric orbits of the two stars as they twirl around each other every 41 days like figure skaters. The planet, which was discovered by NASA's Kepler mission, orbits in a circle around both of the stars every 229 days. The larger of the stars is about 69 percent of the mass of the sun, and the smaller is about 20 percent of the sun's mass. The planet is about the mass of Saturn. All three bodies orbit in the same plane, which is why Kepler can observe the various planetary and stellar eclipses.
Image credit: NASA/JPL-Caltech/T. Pyle
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."

A research team led by Laurance Doyle of the SETI Institute in Mountain View, Calif., used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars, to search for transiting planets. Kepler is the first NASA mission capable of finding Earth-size planets in or near the "habitable zone," the region in a planetary system where liquid water can exist on the surface of the orbiting planet.

Scientists detected the new planet in the Kepler-16 system, a pair of orbiting stars that eclipse each other from our vantage point on Earth. When the smaller star partially blocks the larger star, a primary eclipse occurs, and a secondary eclipse occurs when the smaller star is occulted, or completely blocked, by the larger star.

Astronomers further observed that the brightness of the system dipped even when the stars were not eclipsing one another, hinting at a third body. The additional dimming in brightness events, called the tertiary and quaternary eclipses, reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This showed the third body was circling, not just one, but both stars, in a wide circumbinary orbit.

The gravitational tug on the stars, measured by changes in their eclipse times, was a good indicator of the mass of the third body. Only a very slight gravitational pull was detected, one that only could be caused by a small mass. The findings are described in a new study published Friday, Sept. 16, in the journal Science.

"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.

"Working in film, we often are tasked with creating something never before seen," said visual effects supervisor John Knoll of Industrial Light & Magic, a division of Lucasfilm Ltd., in San Francisco. "However, more often than not, scientific discoveries prove to be more spectacular than anything we dare imagine. There is no doubt these discoveries influence and inspire storytellers. Their very existence serves as cause to dream bigger and open our minds to new possibilities beyond what we think we 'know.'"

For more information about the Kepler-16 discovery, visit:


For more information about NASA’s Kepler Mission, visit:


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