Planet Found Orbiting Two Stars at a Perfect 90-Degree Angle
Astronomers using ESO’s Very Large Telescope have discovered a truly bizarre planet — one that orbits two stars at a perfect 90-degree angle.
This “polar planet” circles a rare eclipsing pair of brown dwarfs, making it the first confirmed world with this kind of alignment. It was a surprising and accidental find, defying expectations and proving that planet formation in extreme orbital setups is not only possible — it’s real.
Hints of Polar Planets Come to Life
In recent years, scientists have found several planets orbiting two stars at once — similar to the fictional planet Tatooine from Star Wars. Typically, these planets orbit in the same plane as the stars themselves. While researchers have long suspected that planets could also form in perpendicular, or polar, orbits around binary stars — and have even observed planet-forming discs tilted this way — there had been no direct evidence of a planet on such an orbit until now.
Confirming the Unexpected
“I am particularly excited to be involved in detecting credible evidence that this configuration exists,” says Thomas Baycroft, a PhD student at the University of Birmingham, UK, who led the study published today (April 16) in Science Advances.
The unprecedented exoplanet, named 2M1510 (AB) b, orbits a pair of young brown dwarfs — objects bigger than gas-giant planets but too small to be proper stars. The two brown dwarfs produce eclipses of one another as seen from Earth, making them part of what astronomers call an eclipsing binary. This system is incredibly rare: it is only the second pair of eclipsing brown dwarfs known to date, and it contains the first exoplanet ever found on a path at right angles to the orbit of its two host stars.
Using ESO’s Very Large Telescope (VLT), astronomers have found an exoplanet orbiting a pair of peculiar stars at an angle of 90 degrees. There have previously been hints that these so-called polar planets around two stars could exist, but we now have clear evidence that this is the case. This special system was found by observing the orbital path of the two stars being pushed and pulled in a way that could only be explained by the presence of a planet on a polar orbit. This video summarizes the discovery, explaining the nature of these peculiar stars and the method astronomers used to find this odd planet. Credit: ESO
A Planet Unlike Any Other
“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,” says co-author Amaury Triaud, a professor at the University of Birmingham.
The team found this planet while refining the orbital and physical parameters of the two brown dwarfs by collecting observations with the Ultraviolet and Visual Echelle Spectrograph (UVES) instrument on ESO’s VLT at Paranal Observatory, Chile. The pair of brown dwarfs, known as 2M1510, were first detected in 2018 by Triaud and others with the Search for habitable Planets EClipsing ULtra-cOOl Stars (SPECULOOS), another Paranal facility.
The Puzzle Behind the Orbit
The astronomers observed the orbital path of the two stars in 2M1510 being pushed and pulled in unusual ways, leading them to infer the existence of an exoplanet with its strange orbital angle. “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,” says Baycroft.[1]
“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,” says Triaud. “Overall, I think this shows to us astronomers, but also to the public at large, what is possible in the fascinating Universe we inhabit.”
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