The discovery of an exoplanet orbiting a pair of brown dwarf stars in a unique polar orbit has captivated astronomers. This rare celestial configuration, observed using the European Southern Observatory’s Very Large Telescope (VLT), provides the first strong evidence of a “polar planet” circling a binary star system. The findings, published in Science Advances, shed light on the diverse planetary architectures that exist in our universe.
The brown dwarf binary, designated 2M1510, was initially identified in 2018 as an eclipsing binary, meaning the two stars eclipse each other as seen from Earth. This already made 2M1510 a rare find, as it represents only the second known eclipsing brown dwarf binary. Now, with the discovery of exoplanet 2M1510 (AB) b, the system’s uniqueness is amplified.
While most known circumbinary planets (planets orbiting two stars) orbit on a plane roughly aligned with their host stars’ orbital plane, 2M1510 (AB) b follows a polar orbit, perpendicular to the plane of the brown dwarfs. This discovery confirms previous theoretical predictions based on observations of perpendicular planet-forming disks around binary stars. Previously, astronomers had identified 16 circumbinary planets, but none with a confirmed polar orbit.
The research team, led by PhD student Thomas Baycroft of the University of Birmingham, noticed peculiar “pushing and pulling” in the brown dwarfs’ orbital paths. This gravitational perturbation suggested the presence of a third body influencing the binary system.
“We reviewed all possible scenarios, and the only one consistent with the data is if a planet is on a polar orbit about this binary,” Baycroft explained.
Co-author Amaury Triaud, also of the University of Birmingham, added, “A planet orbiting not just a binary, but a binary brown dwarf, as well as being on a polar orbit is rather incredible and exciting.” The discovery was serendipitous, as the observations were not initially intended to search for planets.
This finding highlights the diversity of planetary systems and underscores how much remains to be discovered in the vast expanse of the universe. It offers a compelling example of a planetary configuration unlike any other observed, showcasing the remarkable possibilities that await astronomers.
This unusual polar orbit provides valuable insights into planet formation in complex gravitational environments, challenging existing models and expanding our understanding of how planetary systems evolve. Future studies of 2M1510 (AB) b and similar systems promise to further unravel the mysteries of planetary architecture and dynamics.
