Astronomers claim to have discovered a planet which orbits two suns, like the fictional planet Tatooine featured in the sci-fi film series Star Wars.
An international team, which made the finding through NASA’s Kepler spacecraft, says the planet, called Kepler-16b, is about 200 light years from Earth and is believed to be a frozen world of rock and gas, about the size of Saturn.
It orbits two stars that are also circling each other, one about two-thirds the size of our sun, the other about a fifth the size of our sun. Each orbit takes 229 days; the stars eclipse each other every three weeks or so.
Alan Boss, a researcher at the Carnegie Institution for Science in Washington DC and a member of the team, was quoted by the media as saying, “You would never get constant daylight because the two stars are so close together.
“They would come together in an eclipse every 20.5 days and then move apart again. As their separation increased, they would go down at different times, and that could make cocktail hour hard.”
In fact, the team, led by Laurance Doyle at the Carl Sagan Centre for the Study of Life in the Universe at the Seti Institute in California, spotted the planet after noticing unusual signals in data collected by the Kepler spacecraft.
Images captured by Kepler’s camera showed two stars orbiting each other and producing eclipses as they moved in front of one another. Both stars were small in comparison with our own sun, at about 69 and 20 per cent of the sun’s mass.
On closer inspection, the footage revealed further eclipses that could not be explained by the movement of the two stars, or an additional third star. Instead, a subtle drop in light from the stars, which amounted to a dimming of only 1.7 per cent, was attributed to an orbiting planet.
The astronomers turned next to a ground-based telescope, the Whipple Observatory in Arizona. With this, they monitored the shifting velocity of the heaviest star as it moved around in its orbit.
Those observations gave Mr. Doyle’s team the details they needed to reconstruct the orbits of the stars and its planet.
They showed that the two suns orbit each other every 41 days at a distance of about 21 million miles. The planet completes a circular orbit around both stars every 229 days at a distance of 65 million miles, according to the findings published in the Science journal.
Josh Carter, another team member, added: “Kepler-16b is the first confirmed, unambiguous example of a circumbinary planet — a planet orbiting not one, but two stars. Once again, we’re finding that our solar system is only one example of the variety of planetary systems nature can create.”