Astronomers confirmed GJ 887 d as the second-closest known habitable-zone planet to Earth, orbiting a quiet red dwarf star just 10.7 light-years away. The March 2026 finding in Astronomy & Astrophysics resolves a six-year debate over whether the signal was a true world or stellar noise.
The Quiet Star 10.7 Light-Years Away
The recently confirmed super-Earth orbits a red dwarf better known by its catalogue entries as Lacaille 9352 and HD 217987.
At visible wavelengths, the host star ranks among the brightest red dwarfs in the night sky. Yet it remains just beyond normal naked-eye visibility with a magnitude of 7.39. It possesses roughly half the mass of our Sun, less than four percent of its luminosity, and a surface temperature of approximately 3,688 kelvin.
Overcoming Decades of Stellar Noise
Detecting GJ 887 d required untangling a difficult astrophysical puzzle. A planet tugs on its host star through gravity, creating a subtle Doppler wobble in the star’s light. For years, however, starspots and magnetic activity competed to produce nearly identical signals.
Researchers first identified two inner planets in the system back in 2020. Those worlds, GJ 887 b and GJ 887 c, complete their orbits in 9.3 and 21.8 days respectively. The same data revealed a third rhythm near 50.7 days, but early analysts treated the signal as dubious because the star’s rotation period sat close to 39 days. A loose observing schedule easily blurred the two together, especially since the planet’s gravitational pull moves the star by a mere 1.7 meters per second—roughly the speed of a walking human.
New Instruments and Bayesian Evidence
The definitive confirmation appeared in March 2026 in Astronomy & Astrophysics. Christian Hartogh and his collaborators returned to the system with a massive new dataset. The analysis relied on 101 new radial-velocity measurements from HARPS, a precision spectrograph on the European Southern Observatory’s 3.6-metre telescope in Chile. Researchers also incorporated 12 measurements from the ESPRESSO instrument stationed on the Very Large Telescope.
By capturing daily observations across two full stellar rotations, the team separated the magnetic noise from planetary motion. They applied a Gaussian-process model to account for the stellar activity. The 50.77-day signal remained steady, yielding strong Bayesian evidence and a radial-velocity detection of about 4.6 sigma. NASA’s Exoplanet Archive now lists GJ 887 d as a confirmed world.
Super-Earth Mass and Atmospheric Survival
GJ 887 d is classified as a super-Earth. According to NASA, the planet carries a mass at least 6.1 times that of Earth. While that year is far shorter than Earth’s, the star’s cool nature places the planet firmly within the habitable zone where conditions could potentially support liquid water.
GJ 887 offers a notable exception. The star displays unusually low flare activity, preserving a calm environment that greatly improves the odds of a protective atmosphere surviving around the super-Earth.
Why Direct Atmospheric Study Remains Out of Reach
Despite its close distance, examining the planet’s atmosphere directly will test current technology. GJ 887 d does not transit across the face of its star from our vantage point. Astronomers cannot analyze filtered starlight passing through an atmosphere during a transit event.
Instead, researchers must rely entirely on the radial velocity technique. Experts note that GJ 887 d rests on the absolute edge of detectability for proposed future instruments like the Habitable Worlds Observatory, leaving the detailed composition of its atmosphere unmeasured for now.
