June 25, 2026
In a landmark achievement for modern astronomy, the Subaru Telescope in Hawaiʻi has successfully revealed a hidden giant planet and a rare “failed star” in two separate discoveries. These findings represent the first major successes of the OASIS (Observing Accelerators with SCExAO Imaging Survey) project, an innovative international initiative that combines ultra-precise space-based data with the sharpest ground-based imaging ever achieved . The discoveries not only showcase the extraordinary capabilities of the Subaru Telescope but also provide a crucial stepping stone for NASA’s upcoming Roman Space Telescope, which will test new tools designed to directly image Earth-like planets .
For decades, directly photographing exoplanets has been one of astronomy’s greatest challenges. Less than one percent of known stars are home to massive planets or brown dwarfs that can be directly photographed with current telescopes . Even when these objects are young and still glowing from the heat of their formation, they are vastly dimmer than the stars they orbit; their faint light is often overwhelmed by the intense brightness of their host star . For astronomers, the long-standing challenge has not just been how to see these objects, but knowing where to search in the first place.
The OASIS survey addresses this by analyzing astrometric data from the European Space Agency’s Hipparcos and Gaia satellites, which track the tiny “wobbles” in a star’s motion caused by the gravitational pull of an unseen companion . Once a star shows the tell-tale signs of being tugged by an invisible object, the survey turns the Subaru Telescope toward it, allowing the team to capture images of worlds that would otherwise remain hidden in the glare of their star .
One of the new discoveries, HIP 54515 b, is a super-Jupiter that has nearly 18 times the mass of Jupiter. It orbits a star located 271 light-years away in the constellation Leo, at a distance comparable to that of Neptune in our own solar system . The significance of detecting this planet is highlighted by the difficulty of its observation; from Earth, the planet and its star appear incredibly close together on the sky. The separation between them is comparable to spotting a baseball from 100 kilometers away .
Dr. Thayne Currie, the Principal Investigator of OASIS, explained, “HIP 54515 b was seen at just 0.15 arcseconds from its host star. This observation required the extremely sharp images provided by SCExAO” . The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system is what makes such a challenging observation possible, essentially blocking out the blinding light of the star to reveal the faint planet . This discovery adds a new data point to a growing understanding that super-Jupiters often have more eccentric orbits than lower-mass gas giants, suggesting a formation history different from that of planets in our own solar system .
The second object, HIP 71618 B, is a brown dwarf located 169 light-years away in the constellation Bootes, with a mass about 60 times that of Jupiter . Brown dwarfs are often referred to as “failed stars” because they form in a similar way to stars but never gather enough mass to ignite the nuclear fusion of hydrogen in their cores . While a fascinating scientific discovery in its own right, HIP 71618 B holds a special significance for the future of exoplanet research.
It has been identified as the first perfect test target for NASA’s upcoming Nancy Grace Roman Space Telescope’s coronagraph technology demonstration, scheduled for launch in 2027 . This technology is essential for future missions that aim to directly image Earth-like planets around other stars—objects that can be ten billion times fainter than the stars they orbit . Until the discovery of HIP 71618 B, astronomers had not identified a single confirmed target that met the strict criteria required for this vital test.
Its host star is bright, the brown dwarf sits at an ideal position, and at the Roman Coronagraph’s operating wavelengths it will appear faint enough to properly evaluate the new technology . Dr. Masayuki Kuzuhara, the Deputy Principal Investigator of OASIS, stated, “With innovative observation instruments like SCExAO and the world-class observation environment of Maunakea, the Subaru Telescope will continue to produce groundbreaking discoveries as a forefront observation facility” . Together, these discoveries highlight the power of a coordinated approach, combining precise measurements from space with advanced imaging from the ground to find planets and brown dwarfs that would otherwise remain hidden in starlight .
