Oversized star Betelgeuse smaller, closer than expected

Photo credit: ALMA (ESO / NAOJ / NRAO) / E. O’Gorman / P. Kervella

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

Dr. Study led by Meridith Joyce of the Australian National University (ANU) not only gives Betelgeuse a new life, but also shows that it is both smaller and closer to Earth than previously thought.

Dr. Joyce says the supergiant – who is part of the Orion constellation – has long fascinated scientists. But it’s been acting strange lately.

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

“This led to speculation that it might explode soon. However, our study offers a different explanation.

“We know that the first dimming event involved a cloud of dust. We found that the second minor event was likely due to the star’s pulsations.”

Using hydrodynamic and seismic models, the researchers were able to learn more about the physics that drive these pulsations – and get a clearer idea of ​​what stage of their life Betelgeuse is in.

According to co-author Dr. Shing-Chi Leung from the University of Tokyo confirmed the analysis Pressure waves-essentially, Sound waves– were the cause of Betelgeuse’s pulsation. ”

“Right now, helium is burning at its core, which means it is nowhere near exploding,” said Dr. Joyce.

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

The co-author Dr. László Molnár of the Konkoly Observatory in Budapest said the study also showed how big Betelgeuse is and how far it is from Earth.

“The actual physical size of Betelgeuse has been a mystery – previous studies suggested it might be larger than Jupiter’s orbit. Our results suggest that Betelgeuse is only two-thirds of that, with a radius 750 times the radius of the Sun. “said Dr. Molnár.

“Once we got the physical size of the star, we could determine its distance from Earth. Our results show it 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 the explosion to have any significant impact here.

“It’s still a big deal when a supernova goes off. And this is our closest candidate. It gives us a rare opportunity to examine what is happening Stars so before they explode, “said Dr. Joyce.

The study was funded by the Kavli Institute for Physics and Mathematics of the Universe (WPI) at the University of Tokyo and supported by the ANU Distinguished Visitor’s Program. Researchers from the USA, Hungary, Hong Kong and the UK, as well as Australia and Japan, were involved.

The study was published in The Astrophysical Journal.

Betelgeuse continues to darken and decrease to 1.506

More information:
Meridith Joyce et al. Standing on the shoulders of giants: New mass and distance estimates for Betelgeuse through combined evolutionary, asteroseismic and hydrodynamic simulations with MESA, The astrophysical journal (2020). DOI: 10.3847 / 1538-4357 / abb8db

Quote: Supergiant Star Betelgeuse smaller, closer than expected (2020, October 16), accessed on October 16, 2020 from https://phys.org/news/2020-10-supergiant-star-betelgeuse-smaller-closer.html

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