Evidence for a polar circumbinary exoplanet orbiting a pair of eclipsing brown dwarfs.

One notable example of exoplanet diversity is the population of circumbinary planets, which orbit around both stars of a binary star system. There are, so far, only 16 known circumbinary exoplanets, all of which lie in the same orbital plane as the host binary. Suggestions indicate that circumbinary planets could also exist on orbits highly inclined to the binary, close to 90°, polar orbits. No such planets have been found yet, but polar circumbinary gas and debris discs have been observed, and if these were to form planets, then those would be left on a polar orbit. We report strong evidence for a polar circumbinary exoplanet, which orbits a close pair of brown dwarfs that are on an eccentric orbit. We use radial velocities to measure a retrograde apsidal precession for the binary and show that this can only be attributed to the presence of a polar planet.