Astronomers Discover a Unique Planet With a 300-Year Orbit Around Twin Stars

Astronomers have identified a remarkable new exoplanet that mirrors the cinematic sunsets of Tatooine, the twin-sun desert world from Star Wars. Named HD 143811 AB b, this newly confirmed planet challenges existing theories with its extraordinary 300-Earth-year orbit around two closely bound stars — the tightest binary system in which a planet has ever been directly imaged.

Located approximately 446 light-years from Earth, the system immediately stood out to researchers. Directly detecting planets around twin stars is exceptionally uncommon, making this discovery a valuable window into how planetary systems behave when influenced by not one, but two stellar gravitational forces.

The planet was identified by a team led by Jason Wang, assistant professor of physics and astronomy at Northwestern University. Instead of using newly captured observations, the team meticulously revisited older data, demonstrating how reanalysis of archival telescope records can still reveal unseen celestial objects.

The researchers examined eight years of imagery from the Gemini South telescope, specifically using the Gemini Planet Imager (GPI) — a device built to block interfering starlight in order to spot faint planetary bodies. Despite having scanned more than 500 stars during its mission and identifying just one new planet, the team decided to revisit the dataset with renewed analytical techniques.

By comparing archived GPI data from 2016–2019 with follow-up images from the W. M. Keck Observatory, astronomers confirmed that a faint moving object shared identical motion with its host star — a key signature of a bound planetary companion. An independent study from the University of Exeter further validated the planet’s light spectrum, reinforcing the difficulty of identifying such distant, faint worlds.

A Giant, Young, and Unusually Positioned Planet

Further analysis revealed that HD 143811 AB b is a massive gas giant, roughly six times the size of Jupiter, and still radiating leftover heat from its formation. Though about 13 million years old — a mere infant in astronomical terms — it is surprisingly mature in structure.

Its orbit is particularly striking. Even though it lies closer to its binary suns than any similar planet captured through direct imaging, its vast orbital path still requires nearly three centuries to complete a single revolution.

The host stars themselves dance around each other every 18 Earth days, creating an extreme gravitational environment. How such a large world formed and survived in this turbulent region remains an open question for astronomers.

“It’s still unclear exactly how it operates,” Wang noted. “We’ve only discovered a handful of planets like this, so we don’t yet have enough information to fully assemble the picture.”

The discovery is especially valuable because it helps decode the complex physics of three-body orbital interactions. “Only a tiny fraction of the 6,000 known exoplanets orbit binary stars,” Wang explained. “This is the rare kind of system where we can observe both the planet’s orbit and the binary stars’ orbit simultaneously, making it scientifically fascinating.”

The team plans to continue observing the system as the GPI undergoes a major upgrade before moving to Gemini North, Hawaii, as GPI 2.0. Researcher Nathalie Jones has already applied for additional telescope time to map the evolving orbital paths. “We want to track the planet and the motion of the binary stars over time,” she said.

Could More Hidden Worlds Be Waiting in Old Data?

Encouraged by this unexpected discovery, Jones and Wang are now combing through older astronomical archives to hunt for additional overlooked planets.

“There are a few suspicious objects, but we can’t yet confirm what they are,” Jones noted, raising hopes that more rare planetary systems may be hiding in plain sight.

The team’s findings, published on December 11 in The Astrophysical Journal Letters, mark a major step forward in understanding how planets form, migrate, and survive in dynamic dual-sun systems — much like the fictional worlds imagined in a galaxy far, far away.