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1 min read Astronomy

Betelgeuse Has Been Hiding a Companion for a Hundred Years

Astronomers pointed instruments at this star for a century without noticing what was sitting right next to it, and it's heavier than anyone guessed.
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The most famous star about to explode has been keeping a secret.

Astronomers now have firm evidence that Betelgeuse, one of the brightest stars in the night sky, is not alone. Using the European Southern Observatory's Very Large Telescope, a team led by French researcher Miguel Montargès obtained the clearest image ever taken of what is likely Betelgeuse B, a companion star that has been orbiting the red supergiant, undetected, for as long as anyone has been looking.

Betelgeuse is a red supergiant in the constellation Orion whose brightness shifts periodically. For decades, astronomers suspected a companion star might explain some of those variations, and searched for one for roughly a hundred years without success. Two studies published in 2024 predicted that December of that year would offer the widest apparent separation between the two stars, the best chance yet to isolate the companion from Betelgeuse's glare. The team observed during that window and spent months processing the data. Montargès said he was startled by how clearly the companion showed up once the images were processed.

The companion also turned out to be a surprise on its own terms. Earlier estimates put its mass at roughly one Sun. The new data suggest something closer to two or three Suns, brighter and heavier than expected.

The identification is not yet final. To confirm the object is truly in orbit, the team will need to detect it again in about a year, on the opposite side of Betelgeuse. If confirmed, astronomers can start asking whether the companion affects Betelgeuse's evolution, and its eventual supernova. Montargès said the central unresolved question now is whether the companion will shape how Betelgeuse evolves going forward.

A century of searching. One December window. One companion hiding in the glare.

Read the full story at ESO, July 28, 2026

Hot Take: Betelgeuse B ran a hundred-year cover in plain sight of one of the most surveilled stars in the sky, and nobody caught on. Even the best operatives usually get exposed faster than that.

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