A Rare, Movie-Star Discovery: A Tatooine-like Planet That Orbits Two Suns Comes Into Clear View
In a finding that sounds straight out of science fiction, astronomers at Northwestern University have directly imaged an exoplanet that orbits two stars. While capturing any planet beyond our solar system on camera is uncommon, catching one that dances around a binary star system is even rarer. This newly observed world stands out even among those: it sits far closer to its two suns than any other directly imaged planet in a binary system—six times closer, in fact, than its peers.
This breakthrough offers an unprecedented glimpse into the dynamics of planets forming and moving in multi-star environments. It also provides a rare opportunity to study how stars and their planets orbit together, allowing astrophysicists to test theories of planet formation amid complexity.
The study is slated for publication on Thursday (Dec. 11) in The Astrophysical Journal Letters. A separate announcement by European researchers from the University of Exeter, published in Astronomy and Astrophysics, confirms the same discovery.
“Among the roughly 6,000 known exoplanets, only a small fraction accompany binary stars,” said Jason Wang of Northwestern, a senior author on the paper. “Of those, only a handful have been directly imaged—meaning we can see both the binary and the planet in the same image. Being able to track the planet and the binary simultaneously on the sky is unique and exciting, and we’re eager to keep monitoring their motion to understand how the three bodies move together.”
Time-lapse footage accompanies the news, illustrating how the planet drifts along its path around the two stars. To reveal the planet in the glare of its bright hosts, researchers had to carefully subtract the stars’ overwhelming light. Two star icons in the visualization mark where the stars would sit relative to the planet. Credit: Jason Wang, Northwestern University.
Wang, a specialist in exoplanet imaging, serves as an assistant professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences, and is affiliated with the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). The study’s lead author is Nathalie Jones, who holds the CIERA Board of Visitors Graduate Fellowship at Weinberg and works with Wang’s group.
A discovery years in the making
The Northwestern team unearthed the exoplanet from archival data collected years earlier. When Wang was a Ph.D. student, he helped commission the Gemini Planet Imager (GPI), a specialized instrument designed to capture images of distant worlds by suppressing the glare from their host stars. GPI operated initially at the Gemini South telescope in Chile, using adaptive optics and a coronagraph to sharpen faint planetary signals around bright stars.
“We launched a sweeping survey, and I traveled to Chile on multiple occasions,” Wang recalled. “Most of my Ph.D. years were spent hunting for planets. Over the instrument’s lifetime, we looked at more than 500 stars and found only one new planet. It underscored how rare exoplanets are, even with powerful tools.”
Nearly a decade later, Jones revisited the data. GPI is being upgraded and will eventually move to Hawaii to join the Gemini North telescope on Mauna Kea. As the Chilean chapter of GPI winds down, Wang decided the time was right to close that chapter of the search.
“I didn’t expect we’d find anything new,” Wang admitted. “But I believed in giving it one thorough pass.”
Tracking a suspicious signal
Jones combed through GPI data from 2016–2019 and cross-checked it with observations from the W. M. Keck Observatory, accessing Northwestern’s resources. This past summer, she noticed something odd: a faint object appeared to move in lockstep with a star, suggesting a bound companion rather than a random interloper.
“Stars aren’t stationary in our galaxy; they glide around the center of the Milky Way,” Wang explained. “We flag objects, then return later to see if they’ve shifted. If a planet is bound to a star, it will share the star’s motion across the sky. If a so‑called planet isn’t moving with the star, it’s usually just a photobombing star passing by.”
Jones added, “We also check the light signature. Stellar light and planetary light have different fingerprints, and what we observed matched a planet’s profile.”
To their surprise, the object turned out to be a planet captured in GPI’s 2016 image, though it had not been recognized earlier. A European team led by the University of Exeter independently reanalyzed the same data and reached the same conclusion this year.
Born after the dinosaurs walked the Earth
The planet is enormous—about six times the mass of Jupiter. It’s hotter than any planet directly imaged in our solar system, yet cooler than many other directly imaged exoplanets. Located roughly 446 light-years away, its distance is often described as “not in our neighborhood, but in the next town over.” The planet’s age is young: formed about 13 million years ago.
That sounds ancient, but in cosmic terms it’s only a blink—about 50 million years after the dinosaurs vanished. Its youth means it still retains a good deal of heat from its birth.
Another striking aspect is how close the planet orbits its binary hosts. The two stars orbit each other incredibly tightly, completing a revolution in just 18 days. In contrast, the planet completes a circuit around the pair in roughly 300 years—slightly longer than Pluto’s orbit around the Sun.
In Wang’s words: “You have a very tight binary dance, with stars whirling each other quickly, and a distant, slow-moving planet orbiting them from afar.”
What’s next
By astronomical standards, this planet sits relatively near its stars: closer than most directly imaged circumbinary planets. While the team isn’t yet sure how this system formed, they speculate that the binary stars formed first, followed by the planet assembling around them.
“Exactly how this works remains uncertain,” Wang said. “We’ve only detected a few dozen planets in such configurations, so we don’t yet have a complete picture.”
Future work will focus on continued observation to decipher formation processes and interactions within the system. Jones is preparing proposals for additional telescope time to monitor both the planet’s orbit and the binary stars’ motion, deepening our understanding of how planets and binary stars influence one another.
The discovery also highlights the ongoing value of revisiting archival data, since fresh analyses can reveal overlooked phenomena. Jones notes that a couple of other suspicious signals remain under review, but their nature is not yet clear.
The study, titled “HD 143811 AB b: A directly imaged planet orbiting a spectroscopic binary in Sco-Cen,” received support from the Alfred P. Sloan Foundation, the U.S. Department of Energy, the National Science Foundation, and the Gordon and Betty Moore Foundation. The Gemini North and Gemini South telescopes comprise the International Gemini Observatory, with funding and operation shared by the U.S. NSF and NOIRLab.
Source links:
GPI+SPHERE detection of a 6.1 MJup circumbinary planet around HD 143811, Astronomy & Astrophysics (open access)
Astrobiology
