Betelgeuse’s recent strange fading was caused by a large cloud of material that the supergiant star exploded in space, a new study suggests.
Bright star Betelgeuse, which forms the shoulder of the constellation Orion (The Hunter), is about 11 times more massive than the sun, but 900 times more voluminous. This swollen state indicates that Betelgeuse is near death, which will come in the form of a violent supernatural explosion.
In the fall of 2019, Betelgeuse began to darken considerably, losing about two-thirds of its luster by February. This dramatic decline sparked speculation that the star̵7;s destruction may have been imminent – perhaps just a few weeks away. (From our point of view, however; Betelgeuse lies about 500 light-years from Earth, so everything we see with the star today happened centuries ago.)
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But the dramatic display of the sky did not happen: Betelgeuse enabled the dark episode and returned to its normal brightness by May of this year. The recovery sparked a new round of speculation, this time about the cause of the obscuration. Some scientists attributed the reductions to one light that blocks the cloud of dust, for example, while others said large dots of stars on the surface of Betelgeuse is likely to be blamed.
A new study strengthens the dust hypothesis, but adds a twist – Betelgeuse himself apparently new cough.
Researchers studied the star in 2019 and 2020 using the NASA icon Hubble Space Telescope. Hubble observations from September to November 2019 revealed large amounts of material moving from the surface of the Betelgeuse to its outer atmosphere at extraordinary speeds – about 200,000 mph (320,000 km / h).
During this three-month eruption, Betelgeuse lost about twice as much space material from its southern hemisphere as usual, study team members said. (Betelgeuse background spill rate is significant, by the way – about 30 million times more than that our sun.)
This superhot plasma, or gas charged with electricity, cools considerably after traveling millions of miles away from Betelgeuse, condensing into dust grains and forming a blocked light cloud, scientists suggested in the new study, which was published in online today (August 13) in Astrophysical Magazine.
“This material was two to four times brighter than the star’s normal brightness,” lead author Andrea Dupree, associate director of the Center for Astrophysics run by Harvard University and the Smithsonian Institution in Cambridge, Massachusetts, said in a statement.
“And then, about a month later, the southern part of Betelgeuse faded noticeably as the star became weaker,” Dupree said. “We think it is possible that a dark cloud will result from the leak that Hubble discovered.”
Additional Hubble observations supported this interpretation. Ultraviolet light data showed that Betelgeuse’s outer atmosphere had returned to normal by February 2020, although the fading at visible wavelengths continued.
It’s unclear what caused the autumn 2019 explosion. But Dupree and co-author of the study Klaus Strassmeier, of the Leibniz Institute for Astrophysics Potsdam in Germany, think it was possible by Betelgeuse regular pulses.
The supergiant star expands and contracts in a cycle of 420 days on Earth. Strassmeier measured the velocity of gas at the Betelgeuse surface using an automated telescope at the Leibniz Institute and found that the explosion occurred during the star’s expansion phase.
Dupree plans to continue studying Betelgeuse with Hubble, and other astronomers will no doubt keep close to the tabs on the star as well. The superhero is quite interesting in his current state, and observations on him would take on even more importance if Betelgeuse were to emerge in the near future.
“No one knows what a star does before it goes supernova, because it has never been noticed, “Dupree said.” Astronomers have examined stars perhaps a year before them going to supernovae, but not within days or weeks before it happened. “But the chance of the star going to the supernova anytime soon is very small.”
Mike Wall is the author of “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), a book on the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.