After a century of suspicion, a team using ESO’s Very Large Telescope has directly imaged what is very likely Betelgeuse B, and it turned out bigger than anyone expected.
For as long as people have looked up at the constellation Orion, Betelgeuse has been there, glowing a distinct orange-red at the hunter’s shoulder. It is one of the most recognizable stars in the night sky and one of the most intensively studied. It has also been, for about a hundred years, a star with a suspected secret.
Now astronomers have the strongest evidence yet that the secret is real. Using the European Southern Observatory’s Very Large Telescope in Chile, a team led by Miguel Montargès of the Observatoire de Paris has obtained the clearest image ever of what is very likely Betelgeuse B, a companion star in orbit around the red supergiant. The findings will appear in the journal Astronomy & Astrophysics.
“This is the conclusion of a century-long quest,” Montargès said. “We have shown that Betelgeuse is not single, it is accompanied by a faint stellar companion.”
A flicker that needed explaining
Betelgeuse is a variable star, meaning its brightness rises and falls over time. Some of those changes stem from the star’s own churning, pulsating interior. But astronomers noticed decades ago that one longer cycle of variation did not fit neatly into that picture, and they began to suspect that something might be orbiting the giant and influencing its light.
Finding that something proved extraordinarily difficult. Betelgeuse is enormous and blindingly bright, and any companion would be comparatively faint and tucked close to it. Picking out a dim star against that glare is a bit like trying to spot a firefly hovering beside a stadium floodlight.
The breakthrough came from timing. Two studies published in 2024 used the star’s brightness variations to predict the companion’s orbit and concluded that in December of that year it would reach its greatest apparent separation from Betelgeuse as seen from Earth, offering the best possible chance of spotting it. Montargès and his colleagues seized the opportunity, observing the star with the VLT in December 2024 and then spending months processing the data.
The moment the result emerged was not a quiet one. “I jumped from my chair when I saw the processed images,” Montargès recalled.
Bigger and brighter than predicted
Part of the surprise was that the detection was possible at all. “Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted,” Montargès said. “Because it is more massive than predicted, we see it!”
Earlier estimates had suggested the companion was roughly as massive as the Sun. The new observations indicate it is about two to three times more massive. That extra heft makes it brighter, which in turn is what allowed the team to separate its light from the glare of its partner.
The discovery is a reminder of how much can remain hidden even in the most familiar corners of the sky. “The fact that we can still discover a nearby companion, more massive and brighter than the Sun, around such a well-studied star is remarkable,” Montargès said. “These are among the best moments in science: seeing something new, unexpected.”
Planet-hunting tools turned on a giant
The image was captured with SPHERE, an instrument on the VLT designed to block out the overwhelming light of a star so that much fainter objects near it can be seen. SPHERE was built primarily to find and photograph exoplanets, which pose the same basic problem: a dim object lost in a bright star’s glow.
Turning that capability on an evolved giant like Betelgeuse was not an obvious bet, but it paid off. “It is remarkable to see how SPHERE and advanced post-processing techniques, originally developed to find exoplanets, also excel at detecting a companion around a massive, evolved star like Betelgeuse,” said co-author Anthony Boccaletti, also an astronomer at the Observatoire de Paris.
In the team’s published image, Betelgeuse itself has been digitally removed, revealing a faint point of light in the predicted position, consistent with the long-sought companion. Other researchers had previously reported a possible direct detection using the Gemini North telescope in Hawaii, but the new VLT image represents the clearest view and the strongest case to date.
Almost certain, but not quite
Montargès is careful not to overstate the result. Confirming that the faint source is truly orbiting Betelgeuse, rather than being a chance alignment or an artifact, requires seeing it move. The plan is to observe it again when it swings around to the opposite side of the star.
“To be certain that the companion is really there, we still need to observe it in one year on the other side of the star, but there is very little space left for doubt,” he said.
A familiar star with an uncertain future
Betelgeuse already has a history of capturing public attention. Several years ago, the star dimmed dramatically and visibly, prompting widespread speculation that it might be on the verge of exploding as a supernova. A team led by Montargès studied that event with the VLT and found a far less dramatic explanation: the star had been temporarily veiled by a cloud of dust it had expelled.
The supernova question, however, is not idle. Betelgeuse is a red supergiant in the late stages of its life, and stars of its type are expected to end in a supernova at some point, though most astronomers expect that day is still a very long way off on human timescales. The presence of a companion adds a new variable to that story. Companion stars can strip material from their partners, alter how they spin and shed mass, and change the details of how they ultimately die.
“The question is truly opened whether this companion is going to have an impact on the evolution of the red supergiant,” Montargès said.
For now, the result offers something both scientific and oddly personal to anyone who has ever found Orion in a winter sky. The bright orange star at the hunter’s shoulder, a fixture of human stargazing for millennia, has had a partner all along. We simply had not been able to see it until now.
Endnotes
- Montargès, M., Boccaletti, A., Flasseur, O., de Koter, A., Milli, J., Kervella, P., Ridgway, S., Bordier, E., Lagadec, E., Dupree, A. K., Backs, F., Calderwood, T., and Morgan, P. “VLT/SPHERE images the candidate companion of Betelgeuse.” Astronomy & Astrophysics (2026, in press).
- European Southern Observatory. “Astronomers find strongest evidence yet that Betelgeuse has a companion.” News release eso2611 via EurekAlert!, July 28, 2026. https://www.eurekalert.org/news-releases/1137503