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It may take another 100,000 years for the giant red star Betelgeuse to die in a fiery explosion, according to a new study by an international team of researchers.
The study, led by Dr. Meridith Joyce of The Australian National University (ANU), not only gives Betelgeuse a new lease of life, but shows that it is smaller and closer to Earth than previously thought.
Dr. Joyce says that the supergiant, which is part of the constellation Orion, has long fascinated scientists. But lately, he has been behaving strangely.
“It is normally one of the brightest stars in the sky, but we have observed two drops in the brightness of Betelgeuse since late 2019,” said Dr. Joyce.
“This generated speculation that it could be about to explode. But our study offers a different explanation.
“We know that the first dimming event involved a dust cloud. We found that the second smallest event was probably due to the pulsations of the star. “
The researchers were able to use hydrodynamic and seismic models to learn more about the physics that drive these pulsations and get a clearer idea of where Betelgeuse is in its life.
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.”
“It’s burning helium at its core right now, which means it’s nowhere near exploding,” Dr. Joyce said.
“We could be looking around 100,000 years before an explosion happens.”
Co-author Dr. László Molnár of the Konkoly Observatory in Budapest says the study also revealed how large Betelgeuse is and its distance from Earth.
“The actual physical size of Betelgeuse has been a bit of a mystery: previous studies suggested it could be larger than the orbit of Jupiter. Our results say that Betelgeuse only extends to two-thirds of that, with a radius of 750 times the radius of the sun, ”said Dr. Molnár.
“Once we had the physical size of the star, we were able to determine the distance from Earth. Our results show that we are only 530 light years away from us, 25 percent closer than previously thought. “
The good news is that Betelgeuse is still too far from Earth for the eventual explosion to have a significant impact here.
“It is still a big problem when a supernova explodes. And this is our closest candidate. It gives us a unique opportunity to study what happens to stars like this before they explode, ”said Dr. Joyce.
The study was funded by the Kavli Institute for Physics and Mathematics of the Universe (WPI), the University of Tokyo, and facilitated by the ANU’s Distinguished Visitors program. Researchers from the United States, Hungary, Hong Kong and the United Kingdom participated, as well as Australia and Japan.
The study has been published in The Astrophysical Journal.
Reference: “Standing on the Shoulders of Giants: New Mass and Distance Estimates for Betelgeuse Through Evolutionary, Astroseismic, and Hydrodynamic Simulations Combined with MESA” by Meridith Joyce, Shing-Chi Leung, László Molnár, Michael Ireland, Chiaki Kobayashi and Ken’ichi Nomoto, October 13, 2020, The Astrophysical Journal.
DOI: 10.3847 / 1538-4357 / abb8db
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