Imagine a planet with two suns in its sky, like Tatooine from Star Wars. Astronomers have now discovered a real-world analogue: the exoplanet HD 143811 AB b, which orbits a binary star system and lies six times closer to its stars than any previously imaged planet in a binary system. Despite this proximity, its year lasts an astonishing 300 Earth years. The study was published on December 11, 2025, in The Astrophysical Journal Letters.

A Discovery Hidden in Old Data

The planet was not found through new observations, but while reanalyzing archival data from the Gemini South telescope and its Gemini Planet Imager (GPI), collected between 2016 and 2019. Natalie Jones of Northwestern University noticed a faint object moving together with the star — a key signature of an orbiting planet.

“Stars don’t stay fixed in the galaxy; they move,” explained Jason Wang, an expert in direct imaging of exoplanets at Northwestern University. “We look for objects and then come back to them later to see whether they’ve moved. If a planet is bound to a star, it moves along with it.”

The same planet was independently confirmed by a team from the University of Exeter. HD 143811 AB b is a gas giant about six times more massive than Jupiter and only 13 million years old — a teenager by cosmic standards, still warm from its formation.

Two Suns and a 300-Year Orbit

The binary stars HD 143811 A and B orbit each other every 18 Earth days, while the planet circles the stellar pair once every 300 years. Although it is closer to its stars than any other known planet in a binary system, its orbit is still enormous. How such a planet formed in this configuration remains a mystery.

“Exactly how this works is still unclear. We’ve only discovered a few dozen such planets, and there simply isn’t enough data yet to build a complete picture,” Jason Wang noted.

Why This Matters

Planets orbiting binary stars are rare — out of roughly 6,000 known exoplanets, only a small fraction belong to such systems. Even fewer have been directly imaged. HD 143811 AB b provides a rare opportunity to study how the gravity of two stars influences planet formation and evolution.

The team has already requested additional telescope time to monitor the motion of both the planet and its host stars. “I want to continue observing this planet and tracking its orbit, as well as the orbit of the binary stars, to learn more about the interactions between binary stars and planets,” said Natalie Jones.

In Brief

Astronomers have discovered the exoplanet HD 143811 AB b, a gas giant six times larger than Jupiter that orbits a binary star system with a 300-year period. It lies closer to its stars than any other known planet in a binary system, yet its formation mechanism remains unknown. This extremely rare case of direct imaging of a planet around a double star offers a new window into how worlds with a “double sunset” are born.