GJ 887 d, a potentially habitable exoplanet orbiting a red dwarf star 10.7 light-years away, has been officially confirmed following a six-year scientific debate over whether the signal was a real world or stellar noise, according to a peer-reviewed study published in March 2026 in Astronomy & Astrophysics.
The Discovery and Confirmation of GJ 887 d
The newly confirmed exoplanet orbits the red dwarf GJ 887—also catalogued as Lacaille 9352 and HD 217987—every 50.77 days. According to Christian Hartogh and his colleagues in their study “RedDots: Multiplanet system around M dwarf GJ 887 in the solar neighborhood,” the planet was initially detected via a faint radial-velocity wobble. However, verifying the signal required cutting through interference generated by the star itself.
Red dwarfs present unique challenges for planet hunters. As Sandra Jeffers and her team noted in their 2020 findings of two inner planets in the system—GJ 887 b and GJ 887 c—stellar activity like rotation, starspots, and magnetic regions can deform spectral lines and mimic a planet’s gravitational tug. For GJ 887 d, the star’s rotation period of approximately 38.7 days sat dangerously close to the suspected 50.77-day orbital period, blurring the data.
Did you know? GJ 887 d causes its host star to wobble at a mere 1.7 metres per second—roughly the speed of a human walking. Astronomers had to detect this repeated motion in light traveling across more than 100 trillion kilometres of space.
To resolve the ambiguity, the RedDots collaboration analyzed 101 new radial-velocity measurements from the HARPS spectrograph at the European Southern Observatory’s 3.6-metre telescope in Chile, alongside 12 measurements from the ESPRESSO instrument on the Very Large Telescope. Combined with archival data totaling 277 nightly binned HARPS observations, the team achieved a 4.6 sigma radial-velocity detection with strong Bayesian evidence supporting the planetary orbit.
What “Second Closest” Means for Habitable-Zone Astronomy
With its confirmation, GJ 887 d ranks as the second-closest known exoplanet located within a star’s habitable zone, sitting just behind Proxima Centauri b, which orbits a star 4.24 light-years away. NASA’s Exoplanet Archive now lists GJ 887 d as a confirmed world within a system that hosts at least four planets.
While 10.7 light-years is an immense gulf—a spacecraft traveling at Voyager 1’s current speed would need more than 100,000 years to reach it—it places the system squarely in Earth’s local stellar neighborhood. This proximity makes the host star bright enough for precise observation, offering future telescopes a distinct advantage over more distant planetary systems.
Unlike the famous TRAPPIST-1 system or Proxima Centauri, GJ 887 does not feature planets that transit across the face of the star from Earth’s perspective. That viewing geometry prevents astronomers from using transit spectroscopy, the primary method James Webb Space Telescope relies on to analyze exoplanet atmospheres.
Understanding the Habitable-Zone Orbit and Climate Limits
GJ 887 d orbits its host star at a distance of about 0.212 astronomical units, or roughly 31.7 million kilometres. Because red dwarfs are much cooler and dimmer than the Sun—GJ 887 has roughly half the Sun’s mass and less than four percent of its luminosity—this close orbit places the planet inside the star’s calculated habitable zone, which spans orbital periods from about 43 to 122 days.
According to the climate models published in the study, the planet receives about 81 percent of the energy Earth gets from the Sun, yielding an unshielded equilibrium temperature of roughly 241 kelvin (minus 32 degrees Celsius). That calculation does not account for atmospheric greenhouse warming.
Pro Tip: Being inside a habitable zone is not a guarantee of liquid water or life. Just as Venus sits near the inner edge of the Sun’s habitable zone with a runaway greenhouse effect, a planet’s actual surface conditions depend heavily on its atmosphere, volatile inventory, magnetic field, and geological history.
Because the radial-velocity method yields only a minimum mass rather than a physical radius, GJ 887 d’s mass is calculated at approximately six times that of Earth. This places it in the “super-Earth” category, though researchers emphasize that such a mass range leaves room for vastly different compositions, from rocky worlds to water-rich or gas-wrapped mini-Neptunes. NASA’s public catalogue currently classifies the planet as Neptune-like, highlighting the uncertainties that remain when a planet cannot be directly measured via transit.
Stellar Activity and Atmospheric Survival
GJ 887 is considered magnetically quiet compared to many red dwarfs, showing low starspot coverage and stable visible brightness between 1998 and 2018. This relative calm suggests the system may spare its planets from the intense stellar stripping that threatens worlds around active stars like Proxima Centauri.
However, archival Hubble observations analyzed in prior research revealed ultraviolet flaring activity that standard visible-light monitoring missed. While the 2026 study models Earth-like stellar-wind conditions in the habitable zone, whether GJ 887 d can retain an atmosphere remains an open question dependent on its magnetic field and historical flare exposure.
Future Detection and Direct Imaging Prospects
Because transit studies are impossible for this system, researchers are eyeing direct imaging as the next frontier. GJ 887 d is expected to reach a maximum apparent separation of about 65 milliarcseconds from its star. According to the discovery paper, this places the system on target lists for proposed space-based concepts including NASA’s Habitable Worlds Observatory and the LIFE interferometer, though separating the planet’s light from the star will test instrumental limits.
Astronomers are also continuing to refine the system’s architecture, probing for orbital inclination and investigating a tentative 2.2-day signal that could point to a fifth, sub-Earth-mass planet candidate.
Frequently Asked Questions
How far away is GJ 887 d?
GJ 887 d is located approximately 10.7 light-years (3.2877 parsecs) away from Earth in the southern sky.
Is GJ 887 d confirmed to be habitable?
No. While the planet orbits within the habitable zone where liquid water could theoretically exist on an Earth-like surface, scientists have not detected an atmosphere, water, or signs of life on the planet.
Why is GJ 887 d called a super-Earth?
Astronomers use the term “super-Earth” to describe planets with minimum masses falling between two and ten times that of Earth. It refers strictly to mass, not composition or surface habitability.
Can we study GJ 887 d with the James Webb Space Telescope?
Direct atmospheric transmission spectroscopy with JWST is not possible because GJ 887 d does not transit (cross in front of) its host star from Earth’s viewpoint.
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