Astronomers capture first images of Betelgeuse's companion star after 100-year search

For over a century, astronomers have speculated about a companion star orbiting Betelgeuse, the prominent red supergiant in the Orion constellation. Now, that speculation has turned into a confirmed observation. An international research team, led by the Paris Observatory, has successfully captured direct images of Betelgeuse B using the European Southern Observatory's (ESO) Very Large Telescope (VLT) in Chile.

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The moment I saw the processed images, I jumped out of my seat.

The companion star was detected at a distance of 1.3 billion kilometers. Betelgeuse, known for its striking red hue and its position in Orion's shoulder, is a star in its final evolutionary stage. It's a red supergiant, estimated to be 15-20 times the mass of our Sun but with a diameter 700-1000 times larger. Its surface temperature is a relatively cool 3,200 degrees Celsius, compared to the Sun's 5,500 degrees Celsius.

Astronomers had long inferred the presence of a companion star due to Betelgeuse's brightness fluctuating on a roughly 2,200-day cycle. Despite persistent efforts over the past century, the companion remained elusive until now. The research team targeted their observation in December 2024, predicting the companion would be at its furthest point in orbit. After months of data analysis, they finally isolated the faint light of Betelgeuse B.

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We expected the companion to be similar in mass to the Sun, but the actual observation revealed a star 2-3 times more massive and brighter than our Sun.

"The moment I saw the processed images, I jumped out of my seat," said Dr. Miguel Montargès of the Paris Observatory, who led the study. "We expected the companion to be similar in mass to the Sun, but the actual observation revealed a star 2-3 times more massive and brighter than our Sun." The team estimates the stars formed around the same time, placing their age between 8 and 10.5 million years. The breakthrough was made possible by the SPHERE instrument, originally designed for exoplanet detection, and advanced image processing techniques that allowed researchers to block Betelgeuse's intense light and identify the fainter Betelgeuse B.

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This is one of the most rewarding moments in science, to discover a new star larger than the Sun around a star that has been studied so many times.

This discovery is significant not just for identifying another star, but also for its implications regarding Betelgeuse's eventual demise. Stars more than eight times the mass of the Sun are destined to end their lives in a supernova explosion. While Betelgeuse's explosion is not expected for tens of thousands of years and is unlikely to harm Earth due to its distance, the presence and nature of its companion star raise new questions for astronomers about the dynamics of such cataclysmic events.

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It is surprising that the precise observation technique used to find exoplanets has also proven to be excellent at finding the companion star of a red supergiant.