Hints emerge of giant planet orbiting Alpha Centauri A
Using Webb's Mid-Infrared Instrument (MIRI) in August 2024, researchers employed a coronagraphic mask to block Alpha Centauri A's light, revealing an object over 10,000 times dimmer than the star and about twice the Earth-Sun distance away. Analysis suggests the object is likely a Saturn-mass gas giant on an elliptical orbit within the habitable zone of a Sun-like star, though it would not support life.
Follow-up observations in February and April 2025 failed to detect the object, leading scientists to simulate millions of possible orbits. They found that in roughly half the scenarios, the planet's position during those months placed it too close to the star for Webb to spot. The team also factored in a 2019 detection of a possible planet by the Very Large Telescope and ensured simulated orbits remained gravitationally stable given the influence of Alpha Centauri B.
These highly challenging observations required custom strategies to overcome the brightness and rapid motion of the target stars. Researchers say confirmation of the planet would mark the closest directly imaged planet to its star, with properties akin to the giant planets in our solar system. Such a finding would deepen understanding of how planets form and endure in binary star systems.
+ Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of - Cen A. I. Observations, Orbital and Physical Properties, and Exozodi Upper Limits
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