GJ 887 d Confirmed as Second-Closest Habitable-Zone Planet

There is something almost comic about the name GJ 887 d. It sounds like a storage code, not a place. The star it circles is better known to catalogues than to the public, and the planet itself has never been photographed. Yet this anonymous-looking system, located 10.7 light-years away, now contains the second-closest confirmed planet in a star’s habitable zone. Only Proxima Centauri b is nearer to Earth.

The confirmation appeared in March 2026 in Astronomy & Astrophysics, where Christian Hartogh and his colleagues reported that a faint wobble detected years earlier really is caused by a planet orbiting the red dwarf GJ 887 every 50.77 days. What makes the discovery compelling is not just its cosmic neighborhood, but the six-year scientific puzzle that preceded it.

Overcoming Stellar Noise to Confirm GJ 887 d

For six years, the signal for GJ 887 d balanced between two explanations: it might have been a genuine planet, or it might have been the star creating an impressively planet-like false signal. The new work makes the planetary explanation much stronger, though it does not prove the world is habitable or inhabited.

The planet was hiding inside the star’s own noise. GJ 887—also known as Lacaille 9352 and HD 217987—is a red dwarf with roughly half the Sun’s mass, less than four percent of its luminosity, and a surface temperature of about 3,688 kelvin. While it is one of the brightest red dwarfs in our sky at visible wavelengths, its magnitude of 7.39 keeps it just beyond normal naked-eye visibility.

In 2020, a team led by Sandra Jeffers reported two inner planets around the star. GJ 887 b completes an orbit in about 9.3 days, while GJ 887 c takes about 21.8 days. Both orbit much closer to their star than Mercury is to the Sun. The same measurements contained a third rhythm near 50.7 days, placing a potential planet in GJ 887’s habitable zone. At the time, researchers treated the signal as dubious and likely related to stellar activity.

Exoplanet astronomy frequently wrestles with this hurdle. Planets tug their host stars toward and away from us via the Doppler effect, shifting spectral lines slightly. Astronomers call this the radial-velocity method. Unfortunately, starspots, bright magnetic regions, and rotation can deform those same spectral lines and produce repeating shifts of their own. For GJ 887 d, the star’s rotation period of 38.7 days sat dangerously close to the suspected 50.77-day planetary period, risking a blurred detection.

Furthermore, the planet makes GJ 887 move by only about 1.7 meters per second—roughly walking speed. Astronomers attempted to identify that repeated motion from more than 100 trillion kilometers away while the star’s surface produced variations of its own.

New HARPS and ESPRESSO Data Strengthens the Case

The RedDots collaboration returned to the system with 101 new radial-velocity measurements from HARPS, a precision spectrograph on the European Southern Observatory’s 3.6-metre telescope in Chile. They also added 12 measurements from the ESPRESSO instrument on the Very Large Telescope. Combined with archival data, the analysis utilized 277 nightly binned HARPS radial velocities and 12 from ESPRESSO.

The breakthrough relied on both increased data volume and daily cadence observing strategies, allowing the team to follow two full rotations of the star rather than gathering scattered snapshots. Hartogh’s team tracked magnetic activity indicators and applied a Gaussian-process model to represent correlated noise from the star. With a flexible description of how stellar activity changes over time, they tested whether a separate 50-day planetary rhythm remained necessary. It did.

The team reported strong Bayesian evidence for GJ 887 d and a radial-velocity detection of about 4.6 sigma. The peer-reviewed paper, titled RedDots: Multiplanet system around M dwarf GJ 887 in the solar neighborhood, supports a system containing at least four planets. NASA’s Exoplanet Archive lists GJ 887 d as confirmed.

Super-Earth Characteristics and Placid Stellar Behavior

Classified as a super-Earth, GJ 887 d possesses a mass significantly larger than our own. While its 50.7-day orbit is much shorter than Earth’s annual trek, its proximity to a relatively cool star means it would likely experience tropical temperatures.

Despite the intense gravity of a super-Earth, its large size could help the planet retain a thick atmosphere—a vital component for maintaining liquid water and supporting potential life. Unlike many volatile red dwarfs prone to stripping atmospheres via flare activity, GJ 887 is remarkably placid. Its low flare activity increases the likelihood that GJ 887 d maintains a protective atmosphere over long periods.

Observational Hurdles Ahead for Future Telescopes

Studying GJ 887 d presents distinct obstacles. The planet does not transit across the face of its star, preventing scientists from directly analyzing its atmosphere by observing blocked starlight. Instead, researchers rely entirely on the radial-velocity method.

Experts note that GJ 887 d may be on the edge of detectability for upcoming space telescopes, such as the proposed Habitable Worlds Observatory. While its confirmed status marks a major step forward, determining the actual environment of this nearby super-Earth remains a task for future generations of instrumentation.