James Webb Telescope Detects Potential Gas Giant at Alpha Centauri.

Researchers at the University of Arizona Steward Observatory, led by Kevin Wagner, an assistant research professor, have reported potential evidence for a gas giant planet orbiting within the Alpha Centauri triple star system. Building upon initial indications from a 2021 publication and utilising data acquired in 2024 with the James Webb Space Telescope’s Mid-Infrared Instrument, the team employed a coronagraphic mask to suppress stellar glare from Alpha Centauri A and subsequently identified a candidate planet, designated S1, located on the opposite side of the star. This detection follows an initial planet candidate, labelled C1, identified in 2019 using the Very Large Telescope operated by the European Southern Observatory in Chile. The potential planet is estimated to possess a mass comparable to Saturn. It orbits at approximately twice the Earth-Sun distance, suggesting a possible residence within the habitable zone of the closest star where liquid water could theoretically exist.

Nearby Star System

The Alpha Centauri star system, located approximately 4.37 light-years from Earth, remains a focal point for exoplanetary research. Recent observations from the James Webb Space Telescope (JWST) suggest the potential presence of a gas giant planet. A collaborative study led by researchers at the University of Arizona Steward Observatory, building upon initial findings reported in 2021, has identified a candidate planet, designated S1, orbiting within the system. The research leverages data acquired with JWST’s Mid-Infrared Instrument (MIRI), employing a coronagraphic mask – an essential tool for blocking the intense light emitted by the parent star, Alpha Centauri A – to enhance the detection of faint planetary signals. This technique is crucial, as the star’s overwhelming luminosity would otherwise obscure any potential planetary emissions.

The candidate planet is estimated to possess a mass comparable to Saturn – approximately 95 times the mass of Earth – and orbits at a distance of roughly two astronomical units (AU) from A. This places it within the region around a star where temperatures could, theoretically, permit the existence of liquid water on a planetary surface, a prerequisite for life as we currently understand it. However, it is crucial to note that S1 is a gas giant and therefore unlikely to host surface liquid water directly. Its potential significance lies in the possibility that its gravitational influence may have facilitated the formation, or preservation, of more minor, rocky planets within the same system. The detection methodology relies on discerning subtle infrared emissions from S1, a consequence of its internal heat and reflected starlight. The JWST’s MIRI, sensitive to mid-infrared wavelengths, is uniquely suited to this task, providing significantly enhanced sensitivity and resolution compared to previous instruments.