If you’ve seen Beetlejuice, you know better than to say his name three times. Astronomers, meanwhile, have spent over a century staring at Betelgeuse, the red supergiant marking Orion’s shoulder, trying to answer a far more down-to-earth question: does it have a companion?
After a hundred years of suspicion, the answer has finally arrived in the form of a photograph. A team led by French astronomer Miguel Montargès has captured the sharpest image yet of what appears to be the secret companion of Betelgeuse. It’s a much smaller star, named Betelgeuse B, orbiting the red giant. Until now, that star existed only as a mathematical prediction.
A century-old hunch about the secret companion of Betelgeuse
The suspicion that a secret companion of Betelgeuse existed isn’t new. It was first proposed roughly a hundred years ago, after astronomers noticed odd brightness variations that a lone star shouldn’t produce. The trouble is that photographing a small star sitting right next to a red supergiant thousands of times brighter is a tough ask. It’s a bit like trying to spot a lit match glued to a stadium floodlight.
The team used the SPHERE instrument on the Very Large Telescope (VLT), run by the European Southern Observatory (ESO) in Chile’s Atacama Desert. Two studies published in 2024 had calculated that December of that year would be the moment when the suspected companion sat furthest from Betelgeuse in its orbit. That timing would make it easiest to distinguish from the giant’s glare. The astronomers bet on that window, and it paid off.
“I jumped out of my chair”
Montargès summed up the discovery with a candor rarely found in a scientific paper: “Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted. Because it is more massive than predicted, we see it!” By several accounts, he actually jumped out of his chair when the processed data confirmed the signal his team had been chasing for months.
The companion turned out to be a surprise in its own right. Instead of the faint, small star the models predicted, Betelgeuse B carries between two and three times the mass of the Sun, considerably more than expected. That extra mass is precisely what made it visible against all odds.
A name with a bit of poetry
The new star already has an informal name: Siwarha, Arabic for “her bracelet.” It’s not a random choice. Betelgeuse’s own name comes from an Arabic phrase usually translated as “the hand of the giant,” so naming the small star orbiting close to that wrist “bracelet” has a certain poetic logic.
The case isn’t fully closed. The researchers themselves say Siwarha’s exact nature still needs confirming, and its orbit needs more watching. The plan is to point the VLT back at Betelgeuse in late 2027, when the companion is expected to appear on the opposite side of the red giant. That should let astronomers triangulate its orbit more precisely and rule out an optical fluke for good.
Betelgeuse, for what it’s worth, is already famous for another reason: it’s a red supergiant in the final stretch of its life. When it eventually goes supernova, likely thousands of years from now, though nobody can rule out tomorrow, it should be visible from Earth even in broad daylight. In the meantime, we now know the secret companion of Betelgeuse, the faithful Siwarha, won’t be going far: the supergiant will take it along, or leave it behind, whenever that moment comes.
You can read the original discovery announcement from the European Southern Observatory (ESO). If you like this kind of recent astronomical discovery, you might also enjoy the Milky Way black hole wind, found after a 50-year search.