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Astronomers Confirm Potentially Habitable Exoplanet in the Solar Neighborhood

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Summary

A team analyzing the nearby M dwarf gj-887 (10.7 ly from Earth) has confirmed a third planet, gj-887-d, orbiting in the star’s habitable zone — only the second confirmed habitable-zone planet within ~10 ly of Earth, after Proxima Centauri b. Using 101 additional harps measurements plus 12 from espresso on the very-large-telescope, the team also detected a fourth planet (GJ 887 e, Earth-mass, 4.4-day orbit) and a probable but unconfirmed fifth (GJ 887 f, ~0.5 M⊕, 2.2-day orbit). A star-rotation period of ~39 days was derived during the new observing campaign, enabling disentanglement of stellar activity from planetary signals. The paper has been accepted for publication in Astronomy & Astrophysics. GJ 887 d is flagged as a prime target for future direct-imaging missions like the habitable-worlds-observatory and LIFE.

Key Claims

  • GJ 887 is one of the closest stars to the Sun (10.7 ly) and one of the brightest M dwarfs.
  • GJ 887 d is a super-Earth with minimum mass ~6 M⊕ and a 51-day orbital period in the habitable zone.
  • GJ 887 e is an Earth-mass planet at 4.4 days (too close to host for habitability).
  • A probable fifth planet (GJ 887 f, ~0.5 M⊕, 2.2 days) falls below the statistical threshold for confirmation.
  • GJ 887 b and c (super-Earths, 9- and 21-day orbits) were reported in a 2020 Science paper via HARPS radial-velocity.
  • The 2020 study couldn’t resolve a 50-day signal (planet vs stellar magnetic activity); renewed activity in the new campaign revealed the ~39-day stellar rotation, enabling confirmation.
  • Only ~70 of the >5,000 known exoplanets meet the Planetary Habitability Laboratory’s habitable-worlds-catalog criteria; GJ 887 d qualifies.
  • GJ 887 d is “only the second confirmed habitable zone planet within about 10 light-years of Earth, after Proxima Centauri b.”
  • GJ 887 d is a top-priority target for future direct-imaging and atmospheric characterization by HWO and LIFE.

Notable Quotes

“At just 10.7 light-years away, GJ 887 d is one of the closest habitable zone planets to Earth, making it one of the most promising targets for future atmospheric characterization — and for answering the question of whether we’re alone.”

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