Betelgeuse first attracted attention in late 2019 when the star, which shines like a red gem on Orion’s upper right shoulder, experienced an unexpected dimming. The supergiant continued to weaken in 2020. Some scientists assumed that the star would explode as a supernova and have been trying to determine what happened to it ever since. Watch the latest news on Channel 7 or stream for free on 7plus » Now, astronomers have analyzed data from the Hubble Space Telescope and other observatories and believe the star experienced a titanic surface mass ejection, losing a significant portion of its visible surface. “We have never seen a massive mass ejection from the surface of a star before. We’re left with something going on that we don’t fully understand,” Andrea Dupree, an astrophysicist at the Harvard & Smithsonian Center for Astrophysics in Cambridge, Massachusetts, said in a statement. “It’s a completely new phenomenon that we can directly observe and resolve surface detail with Hubble. We’re tracking stellar evolution in real time.” The supergiant star Betelgeuse Credit: NASA, ESA, Elizabeth Wheatley (S Our sun regularly experiences coronal mass ejections in which the star releases parts of its outer atmosphere, known as the corona. If this space weather hits Earth, it can have an impact on satellite communications and power grids. But the surface mass ejection experienced by Betelgeuse released over 400 billion times more mass than a typical coronal mass ejection from the sun. If you want to see this content, please adjust your cookie settings. To learn more about how we use cookies, see our Cookie Guide.
The life of a star
Observing Betelgeuse and its unusual behavior has allowed astronomers to watch what happens late in a star’s life. As Betelgeuse burns through fuel in its core, it has expanded to enormous proportions, becoming a red supergiant. The massive star is 1 billion miles (1.6 billion kilometers) in diameter. Eventually, the star will explode in a supernova, an event that could be briefly visible during the day on Earth. Meanwhile, the star experiences some fiery outbursts of anger. The amount of mass that stars lose late in their lives as they burn through nuclear fusion can affect their survival, but even losing a significant amount of their surface mass is not a sign that Betelgeuse is ready to blow up, according to the astronomers. Astronomers like Dupree have studied how the star behaved before, during and after the explosion in an attempt to understand what happened. Scientists believe that a convective plume, stretching more than 1 million miles (1.6 million kilometers) across, originated inside the star. The plume created vibrations and pulses that caused an explosion, peeling off a piece of the star’s outer shell called the photosphere. The piece of Betelgeuse’s photosphere, which weighed many times more than the moon, was released into space. As the mass cooled, it formed a large cloud of dust that blocked the star’s light when viewed through telescopes on Earth. Betelgeuse is one of the brightest stars in Earth’s night sky, so its dimming — which lasted for a few months — was noticeable through observatories and backyard telescopes.
Recovery from the explosion
Astronomers have measured Betelgeuse’s pace for 200 years. The pulse of this star is essentially a cycle of dimming and brightening that restarts every 400 days. That pulse has stopped for now – a testament to how consequential the explosion was. Dupree believes that the star’s internal transport cells that drive the pulse are still reverberating from the explosion, and compared it to the scraping of an unbalanced laundry tub. The telescope data showed that the star’s outer layer has returned to normal as Betelgeuse slowly recovers, but its surface remains elastic while the photosphere rebuilds. “Betelgeuse continues to do some very unusual things right now,” Dupree said. “The interior is kind of bouncing around.” Astronomers have never seen a star lose so much of its visible surface, suggesting that surface mass ejections and coronal mass ejections could be two very different things. Researchers will have a better follow-up chance to observe the mass ejected from the star using the James Webb Space Telescope, which could reveal additional clues through the otherwise invisible infrared light. If you want to see this content, please adjust your cookie settings. To learn more about how we use cookies, see our Cookie Guide.
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