NASA telescope finds largest ‘Tatooine’ planet to date

Artist’s impression of the simultaneous stellar eclipse and planetary transit events on Kepler-1647 b.

The orbits of all previously known circumbinary planets are shown as gray circles. It is the longest orbit of any transiting exoplanet found to date. The research has been accepted for publication in the Astrophysical Journal with Veselin Kostov, a NASA Goddard postdoctoral fellow, as lead author.

The study team members announced their results today (June 13) at the 228th meeting of the American Astronomical Society in San Diego.

The planet Kepler-1647 b, found using the Kepler Space Telescope, orbits two stars in the constellation Cygnus some 3,700 light years from Earth.

Almost half of all Sun-like stars are members of gravitationally-bound binary star systems. NASA’s Kepler Mission has observed almost 3000 short-period (less than 1000 days) eclipsing binaries. Yet if the planet has large moons, they could potentially be suitable for life. All of the previously identified Kepler circumbinary planets are Saturn-sized or smaller.

Astronomers say they have discovered the largest planet outside the solar system that orbits two suns.

This apparent lack of large circumbinary planets and their proximity to the critical stability limit have left astronomers puzzled.

Kepler-1647b is “the tip of the iceberg of a theoretically predicted population of large, long-period circumbinary planets”, co-author William Welsh, also of SDSU, said in the same statement. Being a Jupiter-sized planet, the discovery of Kepler-1647b confirms these predictions.

Although the planet is in the habitable zone — where water that is crucial to life can be liquid — it’s not a good candidate to support life because it’s so big, scientists said.

Researchers are able to detect planets outside the solar system – called exoplanets – when they pass in front of their stars, causing “slight dips in brightness”, the researchers said.

Known as Kepler-1647, after the giant Kepler Space Telescope that spotted it, the planet is 3,700 light-years away – too far to be seen with the naked eye – and approximately 4.4 billion years old.

A now debated theory is dimming by a cloud of comets or the remnants of a shattered planet, but these would not explain data indicating that the star itself has become slightly dimmer over the past 125 years. The long wait is because transiting circumbinary planets on long-period orbits (far from their binaries) are much more hard to detect than close-in planets.