Aug 18, 2020 - Science

Betelgeuse's dimming explained

Betelgeuse star
Betelgeuse as seen by the Hubble Space Telescope. Photo: NASA/ESA/CfA/STScI

Betelgeuse — the red supergiant star — spit out a huge mass of hot gas and plasma that made it look like it had dimmed significantly from Earth's perspective at the end of 2019 and earlier this year, according to new research.

The big picture: Betelgeuse is one of the brightest stars in the night sky and astronomers keep a close watch on it, with the expectation that it may one day explode as a supernova.

  • That explosion could provide an amazing scientific opportunity to study one of these extreme phenomena from close range.

Details: The Hubble Space Telescope observed extremely hot and dense material moving through the atmosphere of Betelgeuse from September to November of last year, according to NASA.

  • The hot material burst from the star, which is in the constellation Orion's shoulder.
  • Once that material was far enough away from Betelgeuse it cooled, forming dust that obscured the supergiant and making it seem dim from Earth, according to the new study in The Astrophysical Journal.
  • "This material was two to four times more luminous than the star's normal brightness," Andrea Dupree, an author of the study, said in a statement. "And then, about a month later, the south part of Betelgeuse dimmed conspicuously as the star grew fainter. We think it is possible that a dark cloud resulted from the outflow that Hubble detected."

What's next: Scientists aren't yet sure if the outburst could be a sign that the star is going to explode anytime soon, and according to recent observations from NASA's STEREO spacecraft, the star appears to be dimming again.

  • "No one knows what a star does right before it goes supernova, because it's never been observed," Dupree added. "Astronomers have sampled stars maybe a year ahead of them going supernova, but not within days or weeks before it happened. But the chance of the star going supernova anytime soon is pretty small."
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