Astronomers Discover Rare Polar-Orbiting Planet in Unusual Double-Brown-Dwarf System
Astronomers have uncovered an extraordinary planet in the Milky Way, orbiting in an unusual way around two failing stars. Unlike most exoplanets, this planet orbits over and under the poles of its parent stars, rather than following the plane of their orbits. Prior to this discovery, only sixteen exoplanets were known to orbit binary star systems, all of which moved in the plane of the stars’ mutual orbits. The discovery of a planet following a polar orbit in such a system has captured the attention of the scientific community, adding a new layer of intrigue to the study of planetary formation.
The two brown dwarfs that the planet orbits had already been identified by astronomers in 2018, using the SPECULOOS Southern Observatory in Chile. Brown dwarfs, often referred to as “failed stars,” are celestial objects that do not possess enough mass to ignite nuclear fusion in their cores. When the researchers turned their attention to the pair using the Very Large Telescope in Chile, they realized that these brown dwarfs, while not full-fledged stars, could still host fascinating systems.
This discovery marks the first time a “polar planet” has been observed orbiting a pair of brown dwarfs. These bodies, which are too small to sustain nuclear fusion, remain a subject of fascination because of their unique characteristics. The planet, designated 2M1510 (AB) b, is the first known exoplanet in such a system, providing solid evidence that fully formed planetary systems can exist around these “failed stars.” The fact that a binary brown dwarf system could support a planet in such an unusual orbit is a breakthrough in our understanding of stellar and planetary formation.
In addition to being a polar-orbiting planet, the system is also only the second pair of eclipsing brown dwarfs ever discovered, where one brown dwarf eclipses the other from Earth’s viewpoint. This rare configuration makes the discovery even more significant. As Amaury Triaud of the University of Birmingham points out, “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 an unexpected bonus, as the team was not originally aiming to find such a system, underscoring the serendipitous nature of astronomical research.