Astronomers have long searched for clues that red supergiant stars have hidden companion stars just out of sight. Betelgeuse. This time, they discovered new evidence. It’s a trail, like the wake of a boat, cutting through Betelgeuse’s upper atmosphere, likely formed by an unseen companion.

Betelgeuse’s reddish hue is It is approximately 650 light years away from Earth.

This bright star is so large that more than 400 million suns could fit inside it. Its relative proximity and brightness have made it popular among astronomers to observe and study the evolution of this giant star.

But despite being so well known, Betelgeuse has some secrets. One of the biggest secrets is why the brightness appears to change every six years, and An invisible star family nicknamed “Betel Buddy” is responsible for this fluctuation.

Hints about the possibility of it being a companion star are: Research results published last yearin which scientists proposed officially naming celestial objects Siwarahaor “Her Bracelet,” which is a fitting Arabic name for Betelgeuse’s companion, meaning “giant’s hand.” (“Erugius” is also the historical Arabic name for the constellation Orion.)

Given its proximity to Betelgeuse, Siwara is likely too small and faint to be seen. Betelgeuse has burned up all the hydrogen in its core, expanded, and is nearing the end of its lifespan.

Now, observations made over the past eight years have revealed Siwarach’s influence on Betelgeuse. This is the discovery of a never-before-seen trace of dense gas moving through the outer atmosphere of the larger star Siwalaha orbits closely.

Shiwara’s trajectory appeared just after the star crossed in front of Betelgeuse as seen from Earth. Astronomers believe that Siwala makes one orbit around Betelgeuse every six years. Therefore, the brightness of larger stars changes every six years. The observation results are new research Accepted for publication in Astrophysical Journal.

“This is like a boat moving through water. The companion star creates a ripple effect in Betelgeuse’s atmosphere that you can actually see in the data,” lead study author Andrea Dupree, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said in a statement.

“For the first time, we see direct signs of this wake, or gas signature, confirming that Betelgeuse does indeed have a hidden companion that shapes its appearance and behavior.”

Betelgeuse has about 15 times the mass and 1,400 times the diameter of the Sun, Dupree said. Wrinkles, on the other hand, are very small, potentially smaller than the sun.

“If we placed Betelgeuse at the center of our solar system, its surface would extend all the way to Jupiter, and the hot atmosphere above it would extend at least six times further out,” Dupree said. “So this companion star is actually pushing through the dense atmosphere of the supergiant star.”

Dupree’s team has been tracking changes in Betelgeuse’s light for years. hubble space telescope So are ground-based observatories such as the Fred Lawrence Whipple Observatory and the Roque de los Muchachos Observatory.

Observations taken both near and far from the star reveal a pattern that suggests the companion star is orbiting Betelgeuse’s vast atmosphere. The researchers recorded changes in the speed and direction of gas in the large star’s outer atmosphere as a result of the disturbance.

Thanks to Hubble, the team was able to observe how Betelgeuse’s deep atmosphere, or chromosphere, responds to Siwalha’s movements, while ground-based observations revealed changes in the extent of the atmosphere.

“What we learn from these latest results is that Siwara appears to ‘stir up’ Betelgeuse’s extended atmosphere as it orbits, leaving a wake that affects what we see from Betelgeuse itself,” said study co-author Morgan MacLeod, a postdoctoral fellow in theoretical astrophysics and a member of the Harvard-Smithsonian Center for Astrophysics’ Institute for Theoretical Computation.

“This wake is evidence of Siwalach’s existence, and it’s also a signature of how such tiny companions can influence what we see of Betelgeuse by modulating the gas and dust around them,” he added.

The result adds support for findings About Shiwara created by Steve Howell and his team in 2025. Howell is a senior scientist at NASA Ames Research Center in California.

His team’s observations suggested that the size of the detected Siwalha also included the larger area around it as it penetrated Betelgeuse’s atmosphere.

“The idea that the plasma wake surrounding the wrinkles is expanding seems consistent with the discovery of a larger, clumpy source rather than just a bare stellar photosphere,” Howell said. He was not involved in the new research.

Tracking Betelgeuse’s behavior and fluctuations could help astronomers better understand other faint, distant giant stars that are difficult to study, McLeod said.

But in recent years, Betelgeuse has thrown astronomers some mysterious curveballs that require some serious detective work to solve.

From late 2019 to early 2020, Betelgeuse dimmed so quickly that experts thought the star was on the brink of exploding into a supernova. Since an event calledgreat dimmingA team of astronomers determined that the star ejected a large dust cloud that temporarily blocked some of its light as seen from Earth.

Additionally, the star exhibits two regular brightness changes, one lasting six years and the other lasting just over a year.

Data collected over the years shows that Betelgeuse’s brightness changes, dimming, then brightening, about every 416 days. The pulsations within Betelgeuse’s core were found to be typical of red supergiant stars.

The long period of 2,100 days was thought to be due to dust clouds, large convective cells on the star, magnetic activity, or an elusive companion star that was always outside the telescope’s optical range.

Within the past year, evidence from multiple research teams has pointed to the presence of shiwalha as the reason.

“With this new direct evidence, Betelgeuse gives us a front-row seat to observe how the massive star changes over time,” Dupree said. “Finding trails from companion stars means we can understand how stars like this evolve, eject material, and eventually explode as supernovae.”

Dupree added that other supergiants with similar long-short fluctuation patterns may also have invisible companion stars.

Jared Goldberg, a researcher at the Flatiron Institute’s Center for Computational Astrophysics, believes the observations are an important piece of the puzzle in understanding the causes of Betelgeuse’s six-year fluctuations. Goldberg previously wrote Research on companion starsbut was not involved in this study.

If astronomers can conclude that the period fluctuations are due to the presence of a second star, Goldberg said, “they can make a direct link to the physics behind the formation and evolution of stars and planets.”

The team is also working on hydrodynamic models to understand how the wake forms behind the wrinkles and reconstruct how it affects Betelgeuse’s brightness, McLeod said.

Edward Guinan, professor of astronomy and astrophysics at Villanova University in Pennsylvania, said the hydrodynamic analysis will provide important information needed to interpret new observations, such as what to expect from the motion of a sun-sized companion star moving through the outer atmosphere of a massive red supergiant star. Guinan has studied Betelgeuse but was not involved in the new research.

Since Siwalha is so close to Betelgeuse, what will be the fate of the small star?

MacLeod believes Siwala’s gravity is drawing it closer and closer to its giant companion star, which could result in a merger within 9,000 years.

“We think it’s possible that the stars may merge before Betelgeuse goes supernova,” MacLeod said. “This could cause gas to fly around, causing Betelgeuse to spin and influence the nature of the eventual supernova.”

According to astronomers’ calculations, Siwala is currently on the far side of Betelgeuse as seen from telescopes on Earth, but is expected to come into view in 2027.

“Further detections will allow refinement of its orbit and provide a better mass for Siwala, which will help explain the evolution of binary star systems, Betelgeuse’s rapid rotation, and the future of the two stars,” Howell said.

Several teams want to find a way to optically detect siwalha.

“Seeing this companion would be the ultimate proof of its implicit existence,” Guinan said. “I can’t wait.”

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