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Webb Uncovers Provisional Saturn-Mass Exoplanet in Alpha Centauri A’s Habitable Zone

Resolving February and April non-detections through orbital simulations, the team readies 2026–27 campaigns with JWST, supported by Roman observations.

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A promotional concept image of Pandora showing a large gas giant in the night sky

Overview

  • In August 2024, JWST’s MIRI instrument revealed a faint mid-infrared point source near Alpha Centauri A, interpreted as a gas giant candidate about the mass of Saturn in the star’s habitable zone.
  • Follow-up observations in February and April 2025 did not detect the source, prompting millions of orbital simulations that incorporate a 2019 VLT sighting to explain its apparent disappearance.
  • Models suggest the candidate spans 1–1.1 Jupiter radii with a mass of 90–150 Earth masses and follows an eccentric 1–2 AU orbit that would periodically hide it behind the star’s glare.
  • If confirmed, it would become the closest directly imaged planet orbiting in the habitable zone of a Sun-like star and challenge theories of planet formation and stability in binary systems.
  • Teams are planning targeted JWST and Nancy Grace Roman Space Telescope observations in 2026–27 to verify the candidate and initiate detailed characterization of its atmosphere and potential moons.