PREVIEW

BY MARK WORGAN

Astronomers have found that the star Betelgeuse - pronounced ‘Beetlejuice’ - has a partner in shine.

Betelgeuse, which is one of the brightest and most recognisable stars in the night sky, is not alone - as it has a companion star.

In fact, it’s just like Michael Keaton’s demon movie character ‘Beetlejuice’, named after the common pronunciation of the star’s moniker, who found an unlikely pal in Winona Ryder’s unruly goth teenager Lydia Deetz.

Using the European Southern Observatory's (ESO) Very Large Telescope (VLT) in Chile, an international team led by French astronomer Miguel Montargès has captured what is believed to be the clearest image yet of Betelgeuse's long-suspected companion star.

It is actually known as Betelgeuse B rather than Lydia Deetz.

The discovery, published in the journal Astronomy & Astrophysics, brings to an end a search that has lasted for around a century.
“This is the conclusion of a century-long quest,” says Montargès.

Betelgeuse, a red supergiant in the constellation Orion, is easily visible to the naked eye and has fascinated astronomers for thousands of years because of its changing brightness.

“We have shown that Betelgeuse is not single, it is accompanied by a faint stellar companion,” says Montargès, astronomer at the Observatoire de Paris - PSL, France, and lead author of the study published today in Astronomy & Astrophysics.

Scientists have searched for evidence of the companion for decades after it was proposed as a possible explanation for the star's variations in brightness. However, previous attempts failed to confirm its existence.

Two studies published in 2024 predicted that December of that year would provide the best opportunity to observe the companion, when it would be at its greatest apparent distance from Betelgeuse. Montargès and his colleagues used the VLT to observe the star during that period before spending several months analysing the data.

“I jumped from my chair when I saw the processed images,” recalls Montargès.
The findings also suggest the companion is considerably larger than previously thought.
“Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted,” explains Montargès. “Because it is more massive than predicted, we see it!”

Earlier estimates suggested Betelgeuse B was roughly the same mass as the Sun. The new observations indicate it is between two and three times more massive.