Betelgeuse Betelgeuse? The bright star Betelgeuse is likely to have a “Betel buddy” star companion.

Betelgeuse, one of the brightest stars in the night sky, may not be on the verge of exploding as a supernova, according to a new study of star brightening and dimming. Instead, recent research shows that the observed pulses of starlight are probably caused by an invisible companion star orbiting Betelgeuse.

Officially named Alpha Ori B, the “Betelbuddy” (as astrophysicist Jared Goldberg calls it) acts like a snowplow during Betelgeuse’s orbit, pushing light-blocking dust out of the way and guiding Betelgeuse. makes it look brighter temporarily. Goldberg and his colleagues present a simulation of this process in a paper accepted for publication in The Astrophysical Journal. The findings will be published on the arXiv preprint server.

“We ruled out all possible inherent variables as to why this brightening or dimming occurred,” said the study’s lead author, a Flatiron researcher at the Flatiron Institute’s Center for Computational Astrophysics. Goldberg says. “The only hypothesis that seems compatible is that Betelgeuse has a companion star.”

Goldberg co-authored the study with Meridith Joyce of the University of Wyoming and László Molnár of the Hunren Astronomy and Earth Sciences Research Center’s Konkoli Observatory in Hungary.

Reveal the “Bethel Buddy”

Betelgeuse is a red giant star, approximately 100,000 times brighter than the Sun and more than 400 million times larger in volume. The star is nearing the end of its life, and when it dies, the resulting explosion will be bright enough to be visible during the day for several weeks.

Astronomers can predict when Betelgeuse will die by effectively “checking the pulse.” This is a variable star, meaning it brightens and dims, pulsating like a heartbeat. Betelgeuse has two heartbeats. One pulsates on a timescale of a little more than a year, and the other on a timescale of about 6 years.

One of these heartbeats is Betelgeuse’s fundamental mode, a pattern of brightening and dimming unique to the star itself. If a star’s fundamental mode is its long-scale pulse, Betelgeuse could be ready to explode sooner than expected. However, if the fundamental mode is that short-scale heartbeat, as some studies have suggested, then that longer heartbeat is a phenomenon called a long secondary period. In that case, this long brightening and dimming would be caused by something outside the star.

Scientists still don’t know exactly what causes the long secondary period, but one leading theory is that the star has a companion star orbiting it and flying through the cosmic dust produced and ejected by the star. A secondary period occurs when the The displaced dust changes the amount of starlight that reaches Earth, changing the star’s apparent brightness.

The researchers investigated whether other processes could have caused the long secondary periods, such as stirring inside the star or periodic changes in the star’s strong magnetic field. After combining data from direct observations of Betelgeuse with sophisticated computer models that simulate the star’s activity, the research team concluded that Betelbuddy was the most likely explanation.

“Nothing else was positive,” Goldberg said. “Essentially, the absence of Bethelbuddy means that something much stranger is happening, something that cannot be explained by current physics.”

The research team has not yet determined exactly what Betelbadi is, but they assume it is a star with up to twice the mass of the Sun.

“It’s hard to say what that companion star actually is, other than giving us mass and orbital constraints,” Joyce says. “A Sun-like star is the most likely type of companion star, but it’s not definitive.”

“My personal favorite and more exotic hypothesis, although my co-authors may disagree, is that the companion star is a neutron star, the core of a star that has already gone supernova.” she says. “But in that case, you would expect to find evidence of that with X-ray observation, but that’s not the case. I think we should look again.”

A new look at an old star

Next, the team will play paparazzi and try to take images of Bethelbadi with telescopes when visibility may open around December 6.

“Our results are based on inference rather than direct detection, so we need to confirm that Betelbuddy actually exists,” Molnár says. “So we are currently working on an observation proposal.”

The researchers note that this work was only possible through team science.

“Laslow as a space observation and data analysis expert, Jared as a massive star researcher and simulator, and me as a 1D modeler, each of us has to look at this problem from very different angles. , this job would not have happened.” Joyce says. “I would especially like to thank the Flatiron Center for Computational Astrophysics for creating an environment that allowed us to bring together such a diverse range of scientists.”

The research team is also excited to have obtained new information about an object that has been studied for many years.

Betelgeuse “has been the subject of countless studies since the dawn of modern astrophysics,” Molnar said. “Yet, there is still room to make important new discoveries, in this case a Sun-like star hiding in plain sight in the massive glow of a red supergiant star. That’s what excites me the most. It is something that makes you