Astronomy: Possible second image of the exoplanet at Alpha Centauri A
There may be an exoplanet orbiting Alpha Centauri A in the zone where liquid water could occur. This has not been confirmed, but there are now two images.
Image of Alpha Centauri, the two stars and that of the suspected exoplanet
(Image: NASA, ESA, CSA, STScI, DSS, A. Sanghi (Caltech), C. Beichman (JPL), D. Mawet (Caltech), J. DePasquale (STScI))
The James Webb space telescope has found new evidence of an exoplanet orbiting Alpha Centauri in the habitable zone, where water could in principle occur in liquid form. This has been made public by the ESA, which speaks of “strong evidence” for its existence.
At the same time, however, those responsible also admit that, following the image in August 2024, two further searches this spring were unsuccessful. This is not surprising: simulations had suggested that the celestial body may have been too close to its star to be found. In any case, these were some of the most challenging observations with a space telescope.
Not the first clue
The first hint of the possible exoplanet was discovered more than four years ago. An image was also presented at that time. It was taken using a special technique on the Very Large Telescope (VLT). However, it was not possible to prove whether the celestial body actually exists. The James Webb space telescope should now provide this proof. Using its Mid-Infrared Instrument (MIRI), the double star system consisting of Alpha Centauri A and B was photographed a year ago. A special mask obscured the light from Alpha Centauri A, but the exoplanet could not be made out in the remaining light pattern either. Only after the light pattern was subtracted based on reference images and with the help of algorithms did the exoplanet appear.
(Image:Â NASA, ESA, CSA, STScI, A. Sanghi (Caltech), C. Beichman (JPL), D. Mawet (Caltech), J. DePasquale (STScI))
Even though the two follow-up observations in February and April of this year did not provide such evidence, the research team is optimistic that it will follow. If the existence of the celestial body is actually confirmed, it would be a milestone for astronomy, says Aniket Sanghi from the California Institute of Technology, who was involved in the work. Of all the celestial bodies whose existence we can infer from more than just indirect data, it would be the one closest to us. It would also be more similar to the giant planets in the solar system than any other exoplanet pictured. Although it lies in the habitable zone, Earth-like life would not be possible on it. On possible moons, however, it is.
Videos by heise
Possible target for interstellar probes
Based on the data collected, the research team believes that the exoplanet could reach the mass of Saturn and is about as far away from Alpha Centauri A as Earth or Mars is from the sun. The fact that it can be imaged directly at all on this comparatively narrow orbit underlines the performance of the space telescope. After all, an object 10,000 times fainter than its star may have been found here. The research group presents the work and the possible proof in two articles that have been accepted for publication in the Astrophysical Journal Letters and are already available for viewing.
Alpha Centauri A and B form a pair of two stars around four light years away from us, which together with the third star Proxima Centauri make up a triple system. The latter is by far the smallest of the three stars and the closest to our sun. This is one of the reasons why the system has long attracted so much interest. Three exoplanets have now been found around Proxima Centauri, while the search for Alpha Centauri is much more difficult. The idea of sending an interstellar mission there has been under consideration for years. The system could be reached in a few decades with technology that is at least conceivable, even if it is not yet anywhere near realistic.
(mho)
