Los Angeles | Scientists, using NASA’s Kepler Space Telescope, have discovered a Jupiter-like planet orbiting a system of two stars, making it the largest such cosmic body ever found. The planet Kepler-1647b, located in the constellation Cygnus, was discovered by astronomers from NASA’s Goddard Space Flight Centre and San Diego State University (SDSU) in in the US.
Kepler-1647 is 3,700 light-years away and about 4.4 billion years old, roughly the same age as the Earth researchers said. The stars are similar to the Sun, with one slightly larger than our home star and the other slightly smaller.
The planet has a mass and radius nearly identical to that of Jupiter, making it the largest transiting circumbinary planet ever found. Planets that orbit two stars are known as circumbinary planets. Using Kepler data, astronomers search for slight dips in brightness that hint a planet might be passing or transiting in front of a star, blocking a tiny amount of the star’s light.
But finding circumbinary planets is much harder than finding planets around single stars, said William Welsh, from SDSU. The transits are not regularly spaced in time and they can vary in duration and even depth, Welsh said. The planet takes 1,107 days – just over three years – to orbit its host stars, the longest period of any confirmed transiting exoplanet found so far.
The planet is also much further away from its stars than any other circumbinary planet, breaking with the tendency for circumbinary planets to have close-in orbits. Its orbit puts the planet with in the so-called habitable zone – the range of distances from a star where liquid water might pool on the surface of an orbiting planet.
Like Jupiter, however, Kepler-1647b is a gas giant, making the planet unlikely to host life. Yet if the planet has large moons, they could potentially be suitable for life. Kepler-1647b is important because it is the tip of the iceberg of a theoretically predicted population of large, long-period circumbinary planets, said Welsh.