Astronomers Find 27 Planet Candidates Orbiting Twin Stars

A Star Wars Day Discovery

A team from the University of New South Wales has detected 27 candidate planets orbiting pairs of stars, a finding that could more than double the existing catalogue of 18 confirmed circumbinary worlds. The study, published in the Monthly Notices of the Royal Astronomical Society and timed for release ahead of May the 4th, Star Wars Day, evokes the iconic twin-sunset scene from Tatooine.

A New Detection Technique

Rather than relying on the standard transit method, which spots planets passing in front of their host stars, the UNSW team used a technique based on apsidal precession. This involves measuring subtle shifts in the orbital patterns of binary stars caused by the gravitational tug of an unseen companion. Using photometric data from NASA's Transiting Exoplanet Survey Satellite, or TESS, the researchers scanned 1,590 eclipsing binary star systems and flagged 27 that showed precession signals too large to be explained by relativistic, tidal, or rotational effects alone.

"We're missing a huge part of the architecture for these systems," said Associate Professor Benjamin Montet. Lead author Margo Thornton, a PhD student just one year into her doctoral research, made the findings.

Candidates Awaiting Confirmation

The planet candidates range from objects as small as Neptune to bodies ten times the mass of Jupiter, scattered between roughly 650 and 18,000 light-years from Earth. The team cautioned that the signals remain degenerate, meaning the same precession signature could arise from a lower-mass planet in a close orbit or a more massive companion farther out.

With a roughly 2% detection rate across the surveyed binaries, Montet suggests there could potentially be thousands, or tens of thousands, of planets waiting to be found with data from the Vera C. Rubin Observatory's upcoming 10-year sky survey.

Why It Matters

More than half of stars in the universe exist in binary or multiple star systems, yet nearly all known exoplanets orbit single stars. Recent complementary research from the University of Lancashire found through simulations that planet formation may actually be easier around binary stars than previously believed, suggesting that circumbinary worlds could be far more common than the current tally implies.

Thornton has begun follow-up observations to confirm or rule out each candidate and hopes to publish results within the next year. If these worlds prove habitable, the implications for the search for life across the cosmos are profound.