18-04-2025
'New' Tatooine-Like Exoplanet Appears to Orbit 2 Failed Stars
Scientists have found evidence of a Tatooine-like exoplanet that orbits two stars instead of one. Unlike the other 15 circumbinary planets to mimic the orbit of Star Wars' most famous planet, though, this one appears to circle failed stars. Astronomers not involved in the research consider it "some of the most direct evidence yet" of this unique type of system.
The planet in question is 2M1510 (AB) b, and while it hasn't yet been observed directly, data strongly suggests that it exists. Its discovery follows that of two strange stars 120 light-years from Earth: a pair of brown dwarfs, otherwise known as failed stars. While one of the brown dwarfs had been on researchers' radar since 2018, it was only found last year to have been two failed stars, which were too light to ignite. The 45 million-year-old brown dwarfs orbit each other every 12 days, circling a small, proper star just 18 light-years away.
But what orbits them? Using the Very Large Telescope (VLT) in Chile, researchers in the United Kingdom and Portugal found that both brown dwarfs orbit in opposition to their own orbital motion. Thanks to new data analysis methods developed by astronomer Lalitha Sairam when she was at the University of Birmingham, the team knew their findings weren't a fluke: Sairam's methods had improved the precision of their observations by a factor of 30. That meant the odd pattern could only be explained by gravitational bumps from another object, which would need to orbit the failed stars at roughly a 90-degree angle.
A visible light image of the two brown dwarfs locked in a binary system. Credit: DESI Legacy Survey/D. Lang (Perimeter Institute)
"We had hints that planets on perpendicular orbits around binary stars could exist, but until now we lacked clear evidence of this type of polar planet," PhD student and lead study author Thomas Baycroft said. "We reviewed all possible scenarios, and the only consistent with the data is if a planet is on a polar orbit about this binary."
Baycroft and his colleagues consider their discovery "serendipitous," as they'd been using the VLT to study the binary brown dwarf system in general, not to find a new planet.
"It is a big surprise and shows what is possible in the fascinating universe we inhabit, where a planet can affect the orbits of its two stars, creating a delicate celestial dance," Baycroft said.
