VLT's SPHERE Obtains the First Direct Image of Betelgeuse B

An international team of astronomers has obtained the first direct image and the most robust evidence to date of a companion star orbiting Betelgeuse. The discovery, led by researchers from the Observatoire de Paris - PSL and based on data from the European Southern Observatory’s (ESO) Very Large Telescope (VLT), concludes a nearly century-long astrophysical debate over the anomalies of the famous red supergiant located in the Orion constellation.

The Photometric Enigma of Betelgeuse

For decades, Betelgeuse’s brightness fluctuations have puzzled the scientific community. The hypothesis of a companion star had been proposed about a century ago to explain these variations, but direct detection always encountered technological limitations and the severe glare caused by the supergiant itself. Interest in the stellar system recently peaked when Betelgeuse’s abrupt dimming raised speculations about an imminent supernova—a phenomenon later attributed to a dust cloud. Validating the existence of a secondary body required observations in a narrow time window, predicted by two robust theoretical studies from 2024, which indicated that in December of that year the companion would reach its greatest angular separation from the main star, making it easier to capture.

Direct Imaging via SPHERE Instrument

To circumvent Betelgeuse’s intense glare and capture the companion’s photon emission, the team led by Miguel Montargès deployed the SPHERE instrument, attached to the VLT in Chile’s Atacama Desert. Originally designed with advanced adaptive optics systems and post-processing techniques for exoplanet detection, SPHERE proved exceptionally capable of isolating Betelgeuse B’s light. Intensive data processing of the December 2024 observations revealed that the secondary star not only exists but possesses around two to three times the mass of the Sun, making it significantly more massive than previous theoretical estimates, which predicted a solar-mass body.

“Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted. Because it is more massive than predicted, we see it!”

Impact on Stellar Evolution and Next Steps

The detection of Betelgeuse B alters the evolution models for the red supergiant’s binary system. The confirmed presence of a companion with up to three solar masses at a relatively close orbital distance raises new thermodynamic and gravitational questions about how this secondary body will affect Betelgeuse’s anticipated supernova explosion. As a next step for data validation and refinement, the researchers plan to conduct new observations within a year, aiming to capture the companion on the opposite side of its orbit. This step will definitively confirm the system’s orbital parameters, eliminating any residual margin of doubt.