Supergiant star Betelgeuse may have a 'buddy' causing it to flicker

Betelgeuse, the tenth-brightest star visible from Earth, is at the center of a surprising finding making waves in the astronomical community. Recent observations challenge long-standing assumptions about the star’s behavior.

Once thought to be solitary, new research suggests the star’s pulsating light may not be an impending supernova, but the presence of an unseen companion star orbiting the bright giant.

Does Betelgeuse have a companion?

The yet-to-be-seen stellar companion has been humorously named “Betelbuddy” by research scientist Jared Goldberg from Flatiron Institute’s Center for Computational Astrophysics. He said it behaves like a “celestial snowplow.”

As it orbits Betelgeuse, the companion star scatters light-obscuring dust, temporarily brightening Betelgeuse’s natural luminosity.

This led the team to explore the idea that Betelgeuse’s observed light pulsing is due to the interference of Betelbuddy.

“We ruled out every intrinsic source of variability that we could think of as to why the brightening and dimming was happening in this way,” said Goldberg. “The only hypothesis that seemed to fit is that Betelgeuse has a companion.”

Goldberg collaborated with Meridith Joyce from the University of Wyoming and László Molnár from Konkoly Observatory at the HUN-REN Research Centre for Astronomy and Earth Sciences in Hungary.

Betelgeuse’s mysterious pulses explained

Betelgeuse, a massive red giant star, is nearing the end of its life, transitioning into its final stages.

The star brightens and dims rhythmically like a celestial heartbeat with a shorter “heartbeat” period lasting just over a year and a longer, more enigmatic cycle spanning six years. The cause behind these mysterious fluctuations has puzzled scientists.

Traditionally, experts attributed the shorter cycle to Betelgeuse’s fundamental mode – an intrinsic pattern of brightening and dimming from within the star.

However, scientists suspected the longer cycle to be influenced by an external factor. This curious external variability led researchers to explore the possibility of an unseen companion star lurking in Betelgeuse’s shadow.

Sowing the seeds of a new theory

Researchers explored this long secondary period and examined whether internal processes within the star like churnings or periodic magnetic field transformations could be the cause.

Leveraging the power of advanced computer simulations and observational data on Betelgeuse, the team gravitated towards the idea of Betelbuddy.

“Nothing else added up,” Goldberg said. “Basically, if there’s no Betelbuddy, then that means there’s something way weirder going on – something impossible to explain with current physics.”

The nature of Betelbuddy remains speculative but logic suggests it’s a star of at least twice the mass of our sun.

“It is difficult to say what the companion actually is beyond providing mass and orbital constraints. A sunlike star is the most probable type of companion, but that is by no means conclusive,” Joyce said.

Confirming Betelbuddy’s existence

Even as the theory takes hold, it is still hypothetical. The experts seek to gather concrete visual evidence of Betelbuddy using telescopic images.

The team will play paparazzi, trying to capture images of the Betelbuddy with telescopes during a potential window of visibility around December 6th.

“We need to confirm that Betelbuddy actually exists, since our result is based on inference, not on direct detection,” said Molnár. “So we’re working on observation proposals now.”

The power of team science

The researchers highlighted the importance of collaboration, noting that this study was only possible through team science.

“Without each of us considering this problem from very different angles – László as an expert in space-based observations and data analysis, Jared as someone who studies and simulates massive stars, and myself as a 1D modeler – the work wouldn’t have been possible,” Joyce said.

“I want to thank the Flatiron Center for Computational Astrophysics in particular for creating an environment in which pulling together such a diverse range of scientists is possible.”

And so, the celestial investigation continues. The discovery of Betelbuddy could redefine scientists’ understanding of Betelgeuse, a star that “has been the target of countless studies since the dawn of modern astrophysics,” Molnár said.

“And yet, there’s still room to make significant new discoveries: in this case, a sunlike star hiding in plain sight, in the immense glare of a red supergiant. That is what excites me the most.”

The study is published in The Astrophysical Journal.

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