The astronomical community is abuzz: researchers have discovered an extremely rare exoplanet orbiting two stars at the closest distance ever recorded. The new object, designated HD 143811 AB b, is located 446 light-years from Earth and resembles the famous planet Tatooine from the Star Wars universe. Unlike that fictional world, however, this planet is real and has already become the focus of close study by experts around the globe.
HD 143811 AB b completes a full orbit around its stars every 300 Earth years, making its path one of the most unusual among all known exoplanets. Its distance from the double star system is six times closer than any previously photographed similar object. This discovery not only expands the boundaries of our knowledge about planetary systems, but also raises new questions for scientists about how planets can form under such complex conditions.
Archived data
Interestingly, HD 143811 AB b was not discovered through new observations, but rather through a reanalysis of archival images taken nearly a decade ago using the Gemini South telescope and the Gemini Planet Imager (GPI) instrument. This device can block out the bright light of stars to reveal faint objects nearby. GPI operated from 2014 to 2022, after which it was sent to the University of Notre Dame in Indiana for upgrades. In the near future, the upgraded GPI 2.0 is expected to be installed on the Gemini North telescope in Hawaii.
A team of astronomers decided to review old data ahead of launching the updated instrument. As one of the project members, Jason Wang from Northwestern University, admitted, no one expected to find anything new, but a thorough check led to an unexpected result. Over the entire period of GPI’s operation, more than 500 stars were studied, and only one of them revealed a new planet—HD 143811 AB b. This highlights just how rare such objects are.
Discovery confirmed
The subsequent analysis was carried out by Nathalie Jones from the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). She compared three years of GPI data with observations from the W.M. Keck Observatory. As a result, scientists detected a faint object moving in sync with one of the stars. This approach helps distinguish a real planet from a background star accidentally caught in the frame: if an object moves together with its star, it is truly gravitationally bound to it.
Additional tests confirmed that HD 143811 AB b is indeed a planet, not reflected light or another astronomical phenomenon. Interestingly, this object was first recorded back in 2016, but at the time it went unnoticed. An independent team from the University of Exeter in the UK reached the same conclusions as their American colleagues.
A giant among planets
Research has shown that HD 143811 AB b is a true giant: its mass is about six times that of Jupiter. The planet is estimated to be 13 million years old, which is considered very young by cosmic standards. For comparison, Earth has existed for 4.6 billion years. Scientists note that such a young planet still retains heat left over from its formation.
The binary star around which HD 143811 AB b orbits is equally fascinating. The two stars are extremely close to each other, completing an orbit around their common center of mass in just 18 Earth days. Despite this, the planet moves along its orbit very slowly—it takes three centuries to complete a single revolution.
Mysteries of formation
Astronomers are still unable to explain exactly how such planets form in binary systems. Only a few dozen such objects are known, and each new discovery brings scientists closer to an answer. According to Jason Wang, there is still not enough data to build a complete picture, so the team plans to continue observing HD 143811 AB b and its stars.
In the near future, scientists intend to request additional telescope time to track the movements of the planet and its parent stars. This will provide greater insight into how such complex systems interact. In addition, researchers are continuing to analyze archival data in search of new exoplanet candidates in binary star systems. Some objects are already raising suspicions, but their nature remains unclear for now.
In case you weren’t aware, the Gemini Planet Imager (GPI) is a unique astronomical instrument designed for the direct imaging of exoplanets and the study of their characteristics. GPI was installed on the Gemini South telescope in Chile and enabled astronomers to capture the first images of planets orbiting other stars. After its upgrade, the instrument will resume operations in Hawaii, opening up new frontiers for the study of planetary systems beyond our Solar System.
