Astronomers spot Star Wars-like planet with two suns

[News_Editor]

Astronomers spot Star Wars-like planet with two suns

2011-09-16 11:42:55 GMT+7 (ICT)

WASHINGTON (BNO NEWS) -- Astronomers have identified the first circumbinary planet, a planet orbiting two stars, similar to the one seen in the 30-year-old Star Wars film.

The planet, which has been dubbed Kepler-16b, is located some 200 light-years from Earth and has been described as cold, gaseous and not thought to harbor life. The planet was detected during NASA's Kepler mission and its discovery is significant as it demonstrates the diversity of planets within the galaxy.

The existence of circumbinary planets had been previously hinted by earlier researches, but the detection now confirms such planets. Kepler detected the planet by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.

According to astronomers, 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. The research also showed that 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.

A research team led by Laurance Doyle of the SETI Institute in Mountain View, California, 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.

"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."

From our vantage point on Earth, scientists detected a pair of orbiting stars that eclipse each other and the new planet in the Kepler-16 system. 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.

However, astronomers said a a third body could exist since observations showed that the brightness of the system dipped even when the stars were not eclipsing one another.

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.

In addition, another good indicator of the mass of the third body was the gravitational tug on the stars, measured by changes in their eclipse times. Only a very slight gravitational pull was detected, one that only could be caused by a small mass.

"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."

In the Star Wars saga, the fictional planet called Tatooine shows a world with a double sunset. Contrary to Kepler-16b, the fictional planet is habitable, and is even the home planet of the saga's main characters Anakin Skywalker (Darth Vader) and Luke Skywalker.

"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.'"

-- © BNO News All rights reserved 2011-09-16