Astronomers have recently detected what they believe to be a newly discovered companion star orbiting Betelgeuse, a red supergiant located in the Orion constellation’s shoulder.

Betelgeuse is among the brightest and most recognizable stars visible from Earth, easily identified by its reddish hue. Though its striking appearance captivates star watchers, scientists have long studied it due to its fluctuating brightness, which remains a mystery. The newly found companion could help clarify these puzzling light variations.

Between late 2019 and early 2020, Betelgeuse dimmed so significantly that some astronomers feared it might be nearing a supernova. This event, known as the “Great Dimming,” turned out to be caused by the star releasing a massive dust cloud that momentarily veiled its light from our view.

This sudden dimming revitalized scientific interest in understanding Betelgeuse’s quirky behavior, particularly its brightness cycle, which repeats about every six years and has defied explanation for decades.

Using a specialized imaging tool on the Gemini North telescope in Hawaii, a team of scientists has now captured hints of a possible companion, unofficially named “Betelbuddy.” This discovery gives support to earlier theories about a nearby stellar partner.

The proposed name for this celestial neighbor is Siwarha, meaning “her bracelet” in Arabic — a fitting title for the companion to Betelgeuse, often translated as the “Hand of the Giant.”

Researchers believe that understanding the interaction between Betelgeuse and this new companion, designated Ori B in a recent paper in The Astrophysical Journal Letters, could reveal the shared destiny of both stars.

A fuzzy image revealed

As a red supergiant, Betelgeuse is enormous. According to lead researcher Steve Howell from NASA’s Ames Research Center, it has a radius about 700 times greater than the sun and carries 18 times more mass. Placing it in our solar system would see Betelgeuse consuming the Earth, the inner planets, and extending beyond Jupiter's orbit. Its brightness ranges between 7,500 and 14,000 times that of the sun.

Though only around 10 million years old, Betelgeuse’s size has caused it to burn through its core hydrogen quickly, and it’s now expanding as it nears its final stage of life.

Regular observations have shown the star pulsates every 416 days, brightening and dimming — a common trait among red supergiants.

Still, Betelgeuse is known for another, less understood cycle — a six-year brightness pattern that has fascinated researchers. “This long-term variation was puzzling,” Howell noted in an email.

In 2024, two separate teams proposed that an unseen partner star could be the cause. Yet telescopes such as Hubble and both NASA’s Chandra X-ray Observatory found no traces, likely due to Betelgeuse’s intense glow and vast size overshadowing any nearby object.

To detect such a faint companion, astronomers needed a visual technique combining high resolution and contrast, explained Jared Goldberg from the Flatiron Institute. Goldberg, who authored a previous study proposing a companion star, was not involved in the new research.

“Earth’s atmosphere poses a challenge,” Goldberg said, “just like how the stars twinkle due to atmospheric movement which scatters starlight.”

The team turned to a device called ‘Alopeke, meaning “fox” in Hawaiian, which uses speckle imaging to take thousands of rapid snapshots of the sky.

“Each exposure is too short to show clear objects, so the result is a pattern of speckles,” explained Howell. However, combining the data removes atmospheric interference and creates a detailed image, allowing faint stars to be seen with precision.

Discovery of a companion

During the 2020 Great Dimming, Howell’s team attempted to observe the area but failed to spot anything — the nearby star was likely obscured by Betelgeuse itself. Then in December, the imaging revealed a soft blue glow just where Goldberg and another team, led by Morgan MacLeod from Harvard-Smithsonian, had predicted the star should be.

The speckle images captured a relatively young, bluish star, not yet fusing hydrogen in its core, and only 1.5 times the sun’s mass.

This companion shines at less than half a percent of Betelgeuse’s brightness, which is why it remained hidden. Also, the two stars are very close — only four times the Earth-sun distance separates them. For perspective, the Earth lies about 93 million miles from the sun.

The color difference between the stars helped in spotting the fainter one. Howell noted, “It’s like trying to distinguish between two car headlights from 50,000 miles away. With split-second exposures of 14 milliseconds and the powerful 8-meter Gemini telescope, we were able to resolve the two stars.”

This is the first time scientists have identified a companion star orbiting a supergiant so tightly, the team stated.

“I expected it to be difficult, but the companion stood out clearly after processing,” Howell said.

MacLeod had compiled over a century of radial velocity data from photographic plates, dating back to 1896, which indicated a repeated six-year orbital shift — a strong hint of a smaller body pulling on Betelgeuse.

“The evidence from the past helped us pinpoint where the companion would be — and there it was,” MacLeod shared. “Howell’s team carried out the crucial observation that confirmed it.”

A challenging future

Though the finding strongly supports earlier predictions, more observations are necessary to fully confirm the companion’s existence. Goldberg noted that speckle imaging, while powerful, can produce uncertain results.

Edward Guinan of Villanova University, who studies Betelgeuse but wasn’t involved in the recent research, said more data is essential. Watching the star follow its expected orbit would solidify the discovery.

“If the companion truly exists,” Goldberg added, “we’ll see it disappear behind Betelgeuse and later reappear on the other side.” Such an opportunity will come in November 2027, when the stars are farthest apart, offering a clearer view.

Like MacLeod, Goldberg and his peers have also observed motion suggesting that Betelgeuse sways due to a gravitational pull from a nearby object. Still, how the companion influences Betelgeuse's periodic dimming remains unclear.

“Interestingly, the dimming happens when the companion is behind Betelgeuse, and it brightens when the companion is in front — the reverse of an eclipse,” Goldberg explained. “It’s likely that Betelgeuse produces dust, and the companion helps shape or disturb it.”

Roughly 30% of similar red giants show this type of brightness cycling. If caused by unseen companions, it may mean such stars are more common. “Studying these systems helps broaden our understanding of how stars and planets form,” Goldberg said.

As for Betelgeuse's future, questions remain. Howell suggests the star and its companion were formed simultaneously, but while the smaller one is still developing, Betelgeuse nears its end. Its massive outer layers may one day engulf the companion.

There are two likely outcomes. Over the next 10,000 years, the companion may drift closer and merge with Betelgeuse.

“It would be like the two stars embracing forever,” Goldberg explained. “Tracking this merger over time might reveal how quickly their orbit is changing.”

Alternatively, if Betelgeuse goes supernova sooner — possibly within this century — the nearby star may be caught in the blast and destroyed. As Howell put it, “Neither star faces a good ending.”