Rare Exoplanet Discovery

In 2018, astronomers made a groundbreaking discovery of a pair of brown dwarf stars orbiting each other in a rare system known as an eclipsing binary. The binary, named 2M1510, has been found to be even more unique than initially believed. Further observations have revealed the presence of an exoplanet, named 2M1510 (AB) b, orbiting its host star at an angle of 90 degrees, also known as a polar orbit, in relation to the brown dwarfs’ orbital plane.

A Polar Planet

The discovery, made using the European Southern Observatory’s (ESO) Very Large Telescope (VLT), is the first time scientists have documented strong evidence of a "polar planet" orbiting a stellar pair, as detailed in a study published in the journal Science Advances. According to Amaury Triaud, a co-author of the study and an astronomer at the University of Birmingham in the UK, "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."

Circumbinary Planets

As of now, astronomers have discovered 16 circumbinary planets, which are exoplanets orbiting two stars. However, these planets’ orbits are roughly on the same plane as the binary stars’ orbit around each other. Before the recent discovery, scientists had only theorized the existence of such a system with a circumbinary planet on a perpendicular orbit, also called a polar orbit, based on clues such as the detection of perpendicular planet-forming disks around pairs of stars. Thomas Baycroft, a PhD student in astronomy and astrophysics at the University of Birmingham and lead author of the study, expressed his excitement, saying "I am particularly excited to be involved in detecting credible evidence that this configuration exists."

The Rare Brown Dwarf Pair

In addition to the exoplanet’s polar orbit, the brown dwarf pair itself is extraordinarily rare, forming an eclipsing binary, meaning their orbital paths make them eclipse each other as we see them from Earth. 2M1510 consists of only the second pair of eclipsing brown dwarfs known to science.

The Discovery

While studying these two brown dwarfs, Triaud, Baycroft, and their colleagues noted that their orbital paths were being strangely "pushed and pulled." This suggested the presence of an exoplanet on an unusual orbital plane, whose gravity the researchers presumably believed was messing with the binary pair. Baycroft added, "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."

A Serendipitous Discovery

The discovery of the exoplanet was serendipitous, as the observations were not collected to seek such a planet or orbital configuration. Triaud concluded, "The discovery…was serendipitous, in the sense that our observations were not collected to seek such a planet, or orbital configuration. As such, it is a big surprise." Overall, this discovery showcases the fascinating possibilities that exist in the universe we inhabit.