A rare planet may orbit brown dwarf pair at right angles

A rare planet may orbit brown dwarf pair at right angles
by Clarence Oxford
Los Angeles CA (SPX) May 22, 2025

A newly identified planetary system, labeled 2M1510, may be home to one of the most unusual planetary orbits ever observed. A candidate planet appears to loop above and below the poles of a pair of brown dwarfs-celestial bodies too massive to be planets yet too light to ignite like stars. These two brown dwarfs orbit each other closely, while a third brown dwarf circles them at a much greater distance.

Most known planetary systems, including our own, share a common trait: planets orbit in a relatively flat, disk-like alignment around their parent star's equator. This alignment also tends to match the star's rotation, forming what astronomers call a coplanar configuration.

However, 2M1510 b, a potential circumbinary planet, may defy this norm entirely. If its existence is confirmed, its orbit would be almost perfectly perpendicular to the orbital plane of the two central brown dwarfs-an orientation known as a polar orbit. Visualize two spinning disks crossing in an X-shape, and you have the essence of this extreme alignment.

Circumbinary planets-those that orbit two stars simultaneously-are rare. Finding one in a polar configuration is unprecedented. Observations from the European Southern Observatory's Very Large Telescope in Chile suggest this could be the first such discovery.

The detection method used by researchers diverges from the standard transit technique, which identifies exoplanets through temporary dimming when they pass in front of a star. Instead, the team employed radial velocity measurements, detecting tiny shifts in a star's spectral lines due to gravitational tugs from orbiting planets. In this case, slight anomalies in the 21-day orbital rhythm of the brown dwarf pair indicate the gravitational influence of a third, unseen object-presumably the polar-orbiting planet.

To date, scientists have confirmed just 16 circumbinary planets among more than 5,800 known exoplanets, most discovered by the now-retired Kepler Space Telescope. Though polar-orbiting debris disks and protoplanetary structures have been observed before, evidence of a fully formed planet in such an orbit remained elusive-until now.

Led by Thomas A. Baycroft, a Ph.D. candidate at the University of Birmingham in the UK, the international research team detailed their findings in the April 2025 issue of Science Advances. NASA entered the planet into its Exoplanet Archive on May 1, 2025. The full designation of the system is 2MASS J15104786-281874, abbreviated as 2M1510.

Research Report:Evidence for a polar circumbinary exoplanet orbiting a pair of eclipsing brown dwarfs