Astronomers Capture Clearest Image Yet of Betelgeuse Companion Star

Betelgeuse is one of the most recognizable stars in the night sky. Sitting in the constellation Orion, the massive red supergiant has captivated skywatchers for millennia. For roughly a century, astronomers theorized that an unseen companion star was driving the giant’s complex brightness fluctuations. While past research hinted at a binary system, direct observational proof remained stubbornly out of reach until a team led by French astronomer Miguel Montargès put the hypothesis to the test.

Capturing the Companion With SPHERE in Chile

The breakthrough came from observations carried out in December 2024 using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in the Atacama Desert of northern Chile. Researchers calculated that the elusive companion would reach its maximum separation from the host star during that month, making it the prime window for detection.

The team applied advanced post-processing techniques originally engineered to find distant exoplanets to peer through the glare of the supergiant. When lead author Miguel Montargès of the Observatoire de Paris finished processing the data, the results caught him entirely off guard. Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted, Montargès recalled, adding: Because it is more massive than predicted, we see it!

“This is the conclusion of a century-long quest. We have shown that Betelgeuse is not single; it is accompanied by a faint stellar companion. I jumped from my chair when I saw the processed images.”

Miguel Montargès, Observatoire de Paris

Mass and Brightness Defy Early Predictions

The newly imaged companion, which carries the formal Arabic-derived name Siwarha, turned out to be far more substantial than theoretical models anticipated according to researchers. Earlier estimates suggested the secondary star would match the mass of our sun. Instead, direct observations revealed a body roughly 2.6 to 3.1 times more massive than the sun, with a diameter 1.8 to two times greater.

While Betelgeuse itself shines about 100,000 times brighter than our sun and spans a physical size 750 to 850 times larger, its newly confirmed companion emits up to 92 times the sun’s luminosity.

Implications for an Anticipated Supernova

The discovery forces astrophysicists to reconsider the evolutionary timeline of the famous red supergiant as outlined in recent findings.

The presence of a massive secondary star throws those calculations into question.

“If the two stars have interacted or will interact, it could delay or accelerate the supernova. We cannot be sure of anything anymore regarding this star.”

Miguel Montargès, Observatoire de Paris

Next Steps for Confirmation

While the research team is confident in the detection, standard astronomical protocol requires tracking the object’s orbital motion across a full cycle. Montargès and his colleagues plan to observe the system in late 2027 when Siwarha swings around to the opposite side of the red supergiant, providing absolute confirmation of its orbital path.