Possible Giant Exoplanet Found in Alpha Centauri A's Habitable Zone

Astronomers may have detected a giant exoplanet orbiting Alpha Centauri A, a Sun-like star located about 4.3 light-years from Earth. The candidate planet lies within the star's habitable zone and could theoretically host liquid water. However, as a likely gas giant, its potential to harbor life is considered low. The findings have been submitted to The Astrophysical Journal Letters.

Alpha Centauri A forms a binary system with Alpha Centauri B, while the red dwarf Proxima Centauri orbits them at a greater distance. To date, Proxima is the only star in the triple system confirmed to host planets. Alpha Centauri A has long been a prime target for planet searches due to its proximity, though its brightness and the glare from its companion star make detection challenging.

A team from the California Institute of Technology used the James Webb Space Telescope's (JWST) infrared capabilities in combination with a coronagraph to block the star's light, capturing signals consistent with a planetary body. Data suggest an orbital distance about twice that of Earth from the Sun, a mass similar to Saturn, and a size close to Jupiter, with an elliptical orbit.

If confirmed, the planet's strong gravity could disturb the habitable zone, affecting the stability of any Earth-like worlds. Two follow-up observations in 2025 failed to detect the object, though simulations indicate it may have been in an undetectable orbital position. The team plans a third observation in August 2026 to verify its existence.

Although unconfirmed, the possible discovery marks a significant advance in exoplanet detection methods. If validated, it would be the first known exoplanet in the habitable zone of a Sun-like star within our galaxy, offering new clues in the search for extraterrestrial life.