Free Astronomy Magazine November-December 2026

companion, more massive and brigh- ter than the Sun, around such a well-studied star is remarkable,” says Montargès. “These are among the best moments in science: seeing something new, unexpected.” Betelgeuse B was directly imaged, meaning the light from the star itself was detected, using the SPHERE in- strument on ESO’s VLT in Chile’s Ata- cama Desert. While there was evidence for the existence of this companion star, including a possible direct detection with the Gemini North Telescope in Hawai ‘ i, USA, this is the strongest evidence for, and clearest image yet of, Betelgeuse B. “It is remarkable to see how SPHERE and advanced post-processing tech- niques, originally developed to find exoplanets, also excel at detecting a companion around a massive, e- volved star like Betelgeuse,” says co- author Anthony Boccaletti, also an T his image is a colour composite made from exposures from the Digitized Sky Survey 2 (DSS2). The field of view is approximately 2.0 x 1.5 degrees. [ESO/Digitized Sky Sur- vey 2. Acknowledgment: Davide De Martin] 21 NOVEMBER-DECEMBER 2026 dicted that in December that year, the companion would be furthest from Betelgeuse and hence easier to spot. Montargès and his team got to work, observing the star with ESO’s VLT in December 2024 and spending several months processing the data. “Honestly, I thought we did not have the sensitivity to detect Betel- geuse B as it was predicted,” ex- plains Montargès. “Because it is more massive than predicted, we see it!” Originally thought to be about as massive as the Sun, the new ob- servations reveal that Betelgeuse B has instead around two to three times the mass of the Sun. “The fact that we can still discover a nearby astronomer at the Observatoire de Paris. “To be certain that the companion is really there, we still need to ob- serve it in one year on the other side of the star, but there is very little space left for doubt,” adds Mon- targès. A few years back, Betelgeuse was the subject of attention from as- tronomers and non-astronomers alike when it visibly started dim- ming. As an evolved supergiant star, Betelgeuse is expected to die in a su- pernova explosion, and the dim- ming led some to speculate it could be about to explode. A group of as- tronomers led by Montargès studied the star with ESO’s VLT, finding it was instead obscured by a cloud of dust. The potential detection of Betel- geuse B will prompt astronomers to investigate how the companion could affect Betelgeuse’s anticipated supernova explosion. “The question is truly opened whether this com- panion is going to have an impact on the evolution of the red super- giant,” concludes Montargès. !