Study Rules Out Giant Planets Around 70 Ophiuchi
Researchers combined a century of measurements with new observations to narrow the search for planets in this nearby binary star system.
Updated on Nov. 7, 2026 in Space
A research team has ruled out planets equal to or larger than Jupiter's mass orbiting the 70 Ophiuchi AB star system, which sits 16 light-years from Earth. The findings narrow the search for smaller worlds in the system.
Why it matters
The system is the third nearest binary to Earth, and eliminating giant planets helps astronomers focus on whether smaller planets could exist there. The work also shows how stellar surface activity can mimic a planet signal in radial-velocity data.
Radial-velocity detection tracks wavelength shifts in starlight caused by a planet's gravitational pull, and the team used the 6.5-meter Magellan Clay Telescope in Chile and the 2.7-meter Harlan J. Smith Telescope in Texas. Smaller planets remain undetected, and the team has not ruled them out.
The players
NASA
The United States space agency is developing the Habitable Worlds Observatory, which is expected to examine the system for smaller planets.
University of Michigan
The public research university's astronomers were members of the team that conducted the study.
The details
William Jacob proposed a planet around the star in 1855, a claim that was later dismissed. The team combined historical radial-velocity measurements with new observations to test whether a giant planet could explain the persistent wobble in the system, and found stellar surface activity was mimicking a planet signal.
Timeline
1855: William Jacob proposes a planet around 70 Ophiuchi AB.
Decades before the study: Astronomers record persistent radial-velocity wobble in the system.
Current study: Team publishes exclusion of giant planets in the system.
Big Picture
The result narrows the candidate list for NASA's planned Habitable Worlds Observatory, which is designed to search for smaller, potentially habitable planets. Eliminating giant planets in this binary system clears the way for more focused searches for rocky worlds.
Finding that giant planets are absent from this system helps astronomers prioritize targets for future telescopes. Readers interested in exoplanet discovery can follow how these searches shape which stars receive the most observing time.
The takeaway
Ruling out one type of planet helps astronomers focus scarce telescope time on the search for smaller, rocky worlds. Careful reanalysis of old data can be as valuable as new observations.
Further reading
Explore more space news to see how astronomers are searching for planets beyond our solar system.
Source note: This article includes information reported by Ecoportal.
