Betelgeuse’s long-lost partner has finally been found

There is a century-old mystery around Betelgeuse, the red super giant glowing on Orion’s shoulders, which can eventually be solved. Astronomers may have discovered the star’s long-term predictive companion using one of the world’s largest telescopes.

Their observations were published on July 24 in the *Astrophysics Magazine Letter, suggesting that this elusively outstanding companion might explain the confusing long-term fluctuations in brightness. The discovery marks the first possible direct imaging of the stars rotating close to the Betelgeuse, which can help reveal the development of giant stars in their final stages before the supernova.

The case of a flashing giant

Betelgeuse is the tenth brightest star in the night sky and has attracted astronomers for hundreds of years. Its light shakes at a strange rhythm, and the simple pulsation model cannot be fully explained. A possible answer came a long time ago: Maybe the Red Giant has a smaller companion star, gravitationally nudged, and triggers periodic darkening. But it is tricky to prove this theory.

Betelgeuse is a huge star, more than 700 times the diameter of the sun, and its blind brightness makes it difficult to detect light objects nearby. The telescope strives to distinguish any excellent companion hidden in its overwhelming glare.

Steve Howell, a senior scientist at NASA’s Ames Research Center, changed in December 2024. The observatory’s high-resolution “Alopeke Speccle camera” allowed his team to bypass atmospheric blur by quickly capturing thousands of split exposures, which were later merged to filter out noise and sharpen the image.

Time is everything

Two previous studies predict that if there were peers, it would briefly emerge from behind Betelgeuse in late 2024, achieving the maximum separation before swinging behind the giant. This narrow window of observation makes Howell and his colleagues try out direct image in just a few days.

Their strategy worked. On December 9, 2024, the team had only 52 mm seconds of weak object imaging in Betelgeuse, which happened to be a prediction of the field model. This proximity and its predicted brightness and orbital angle strongly suggest that it is not a background star, but a true gravitational companion.

“We found separations of 52 milliarcseconds with a position angle of 115 degrees,” the researchers wrote. “As expected, the partner was not detected in 2020 and the predicted separation and position angles were detected in 2024.” The detection had a signal-to-noise ratio of about 1.6, which was moderate, but the match with five independent predictions enhanced the situation.

What kind of star is this?

Based on its estimated brightness and proximity, the team believes that the companion is young, with about 1.6 solar superstars. Probably the pre-media sequence F-type star, which is about 6 amplitudes than betelgeuse and may never be fully mature. Betelgeuse itself has only 10 million years of history and is expected to explode as a supernova in a relatively near-universe future.

Other models come up with a smaller companion, probably only 0.6 solar. However, the newly imaged object looks too bright to make a lower estimate, favoring slightly heavier classification.

Bracelet around giant hand

The team gave the companion a name: “Siwarha”, which originated from Arabic, meaning “her bracelet”. Betelgeuse’s own name can also be traced back to Arabic and refers to the “hand” of giant figures in Orion. The poetic pairing adds cultural resonance to scientific discoveries.

Looking to the future

This detection opens the door to a deeper investigation into the Red Super Giant and its companions. Continuous monitoring is planned, especially when Siwarha reaches its maximum separation point in November 2027. At the time, this vision should once again provide a rare opportunity to imitate stars without the blind influence of Betelgeuse.

“I hope our discovery will inspire other astrophysicists to power the ground telescopes and spot imagers,” Howell said. “This can help unravel the great mysteries in our universe.”

Key Discovery

• NASA scientists may image long-term predicted peer stars as Betelgeuse.
• The detection occurs in the narrow orbital window predicted by past studies.
• This faint companion named Siwarha is only Milliarc of Betelgeuse.
• Siwarha may help explain Betelgeuse’s strange long-term dim cycle.
• The discovery relies on ground spot imaging to overcome atmospheric distortion.

Journal Information

Study: “Maybe direct imaging has discovered stellar companions to Bertelgaya’s mate”
Author: Steve B. Howell et al.
Posted in: Astrophysical Diary LetterVolume 988, Volume 2 (July 24, 2025)
doi: 10.3847/2041-8213/adeaaf

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