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Home / Science / Surprisingly, the Red Giant Betelgeuse behaves smaller and closer to the first thought

Surprisingly, the Red Giant Betelgeuse behaves smaller and closer to the first thought



Illustration of Betelgeuse

Illustration of Betelgeuse. Credit: NASA, ESA and E. Whitley (STScI)

According to a new study by an international team of researchers, it could be another 100,000 years before the giant red star Betelgeuse dies in a fiery explosion.

A study by Dr. Meridit Joyce of The Australian National University (ANU) not only gives Betelgeuse new life, but shows that it is both smaller and closer to Earth than previously thought.

Dr. Joyce says the supergiant – which is part of the constellation Orion – has long fascinated scientists. But lately, it’s been weird.

“It’s usually one of the brightest stars in the sky, but we’ve seen two drops in Betelgeuse’s brightness since late 2019,” said Dr. Joyce.

“It simply came to our notice then. But our study offers a different explanation.

“We know that the first eclipse event involved a cloud of dust. We found that the second smaller event was probably related to the pulsations of the star.

Researchers have been able to use hydrodynamic and seismic modeling to learn more about the physics that drive these ripples – and to get a clearer idea of ​​what phase of their lives Betelgeuse is in.

According to co-author Dr. Shing-Chi Leung of the University of Tokyo, the analysis “confirmed that pressure waves – essentially sound waves – were the cause of the Betelgeuse pulsation.”

“At the moment, it’s burning helium in its core, which means it’s almost going to explode,” Dr. Joyce said.

“We could look at about 100,000 years before the explosion.”

Co-author Dr. Laszlo Molnar of the Konkola Observatory in Budapest says the study also showed how large Betelgeuse is and its distance from Earth.

“The actual physical size of Betelgeuse was a bit of a mystery – previous studies have shown that it may be larger than the orbit Jupiter. Our results show that Betelgeuse is only two-thirds of that, 750 times the radius of the Sun, ”said Dr. Molnar.

“Once we got the physical size of the star, we were able to determine the distance from Earth. Our results show that this is only 530 light years from us – 25 percent closer than previously thought. “

The good news is that Betelgeuse is still too far from Earth for a possible explosion to have a significant impact.

“It’s still a big deal when a supernova erupts. And this is our closest candidate. This gives us a rare opportunity to study what happens to such stars before they explode, ”said Dr. Joyce.

The study was funded by the Institute of Physics and Mathematics of the Cavli Universe (University of Tonic) with the assistance of a program of outstanding visitors to ANU. It was attended by researchers from the United States, Hungary, Hong Kong and the United Kingdom, as well as Australia and Japan.

The study was published in Astrophysical Journal.

Reference: Standing on the Shoulders of Giants: New Estimates of Mass and Distance for Betelgeuse Using Combined Evolutionary, Asterossemic, and Hydrodynamic Simulations with MESA r., Astrophysical Journal.
DOI: 10.3847 / 1538-4357 / abb8db




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