Astronomers using NASA’s James Webb Space Telescope have discovered strong evidence of a giant planet orbiting the star Alpha Centauri A. Located 4 light-years away from Earth, this finding is significant as it would be the closest gas giant to our solar system that orbits in the habitable zone of a Sun-like star.
Alpha Centauri, a triple-star system consisting of Alpha Centauri A and B, as well as the faint red dwarf Proxima Centauri, has long been a target for exoplanet hunting. While there are three confirmed planets orbiting Proxima Centauri, the presence of other worlds surrounding Alpha Centauri A and B has proved challenging to confirm.
We Webb’s observations from its Mid-Infrared Instrument (MIRI) provided strong evidence for the existence of this gas giant planet. However, due to the star’s brightness and close proximity to Earth, making it a challenging target, the team had to devise custom observing sequences to detect the planet.
Initial observations in August 2024 revealed an object over 10,000 times fainter than Alpha Centauri A, separated from the star by about two times the distance between the Sun and Earth. While this detection was exciting, subsequent observations did not reveal any objects like the one identified in August 2024.
To investigate the mystery of the disappearing planet, researchers used computer models to simulate millions of potential orbits. These simulations took into account previous sightings of a potential exoplanet candidate by the European Southern Observatory’s Very Large Telescope and new data from Webb.
According to their findings, if confirmed, this giant planet would be approximately the mass of Saturn orbiting Alpha Centauri A in an elliptical path varying between 1 to 2 times the distance between Sun and Earth. The existence of such a planet would challenge our understanding of how planets form, survive, and evolve in chaotic environments.
The discovery has significant implications for exoplanet science, with future observations by NASA’s Nancy Grace Roman Space Telescope potentially offering unique insights into the size and reflectivity of this gas giant planet.
Source: https://science.nasa.gov/missions/webb/nasas-webb-finds-new-evidence-for-planet-around-closest-solar-twin