How close to Earth could we find the next Earth-like exoplanet? This is what two papers accepted in The Astrophysical Journal Letters hopes to address as a team of more than two dozen researchers announced the discovery of a Saturn-sized world orbiting in the Alpha Centauri triple star system, which is the closest star system to Earth at approximately 4.37 light-years from Earth. This study has the potential to help scientists develop more efficient methods for finding exoplanets beyond Earth, and potentially Earth-like exoplanets.
For the study, the researchers used NASA’s powerful James Webb Space Telescope (JWST) to observe Alpha Centauri A, which is the largest star in the system, in August 2024, February 2025, and April 2025. After obtaining data on the exoplanet candidate in the August 2024 observation, the team was unable to find data in the following two observations. To solve this conundrum, the team used a combination of computer models and data from a 2019 observation of the same exoplanet candidate to ascertain why the February and April 2025 observations didn’t identify it.
In the end, the team not only confirmed the existence of a Saturn’s sized exoplanet, but also that it was orbiting in the habitable zone of its star at approximately 2 astronomical units (AU). For context, Earth orbits our Sun at 1 AU. Additionally, this new exoplanet was discovered using the direct imaging method, which has resulted in confirming only a fraction of exoplanets.
“If confirmed, the potential planet seen in the Webb image of Alpha Centauri A would mark a new milestone for exoplanet imaging efforts,” said Aniket Sanghi, who is a PhD student at Caltech while being second author of the first paper and lead author of the second paper. “Of all the directly imaged planets, this would be the closest to its star seen so far. It’s also the most similar in temperature and age to the giant planets in our solar system, and nearest to our home, Earth. Its very existence in a system of two closely separated stars would challenge our understanding of how planets form, survive, and evolve in chaotic environments.”
JWST continues to push boundaries regarding exoplanet exploration, as its powerful instruments are capable of analyzing the compositions of exoplanet atmospheres to complement its ability to directly image exoplanets.
What new discoveries about the Alpha Centauri triple star system will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: arXiv, arXiv (1), NASA JPL
Featured Image: Artist's illustration of a Saturn-sized exoplanet orbiting in the Alpha Centauri triple star system. (Credit: NASA, ESA, CSA, STScI, Robert L. Hurt (Caltech/IPAC))
