Astronomers have identified the first confirmed exoplanet that orbits its stars at a 90-degree angle, known as a polar orbit. The planet, 2M1510 (AB) b, moves perpendicular to the orbital plane of its host stars.
This planet circles a pair of brown dwarfs—2M1510 AB and 2M1510 C—objects often referred to as “failed stars” due to their insufficient mass to sustain hydrogen fusion. Binary brown dwarf systems are considered rare.
The system lies approximately 120 light-years from Earth in the constellation Libra. This location was confirmed using observations from the Very Large Telescope (VLT) in Chile.
While planets orbiting binary stars have been documented, this is the first known case of a planet on a polar orbit within such a system. Previous studies only suggested such orbits through observations of protoplanetary discs.
Brown dwarfs, typically isolated or in wide binaries, are rarely found as close pairs. This discovery marks only the second known case of eclipsing brown dwarfs—where one passes in front of the other from Earth’s perspective.
Researchers used UVES, a spectrograph at the VLT, to study the motion of the brown dwarfs. Variations in their movement suggested the presence of a third body influencing their orbits—later identified as a planet.
The findings were published on 16 April in Science Advances. The team describes the detection as unexpected, as their observations were not originally intended to identify exoplanets or such orbital configurations.