"We think that the huge bubble that burst from the star's interior before the dimming caused the star's envelope and its interior to move in opposite directions, and, as a result, the star is now pulsating twice as fast compared to its normal cycle."īetelgeuse is an enormous star. "We think the change in the cycle duration is linked to the event that caused the Great Dimming," MacLeod said. In the paper, posted on the online repository Arxiv on May 16, MacLeod and his colleagues, rather than expecting a supernova, predict that Betelgeuse will return within the next five to 10 years to its usual ways, slowing its cycle of brightening and dimming to the normal 400 days. The usual peak brightness, on the other hand, is about 0.3, and now we are only at about 0.1." Back to normal "During the Great Dimming, the magnitude went from 0.8 down to 1.75. "If we compare the current brightening to the Great Dimming, it's really quite negligible," Montargès said. In fact, the star has been this bright previously, he said, albeit only for brief periods of time. Like MacLeod, Montargès thinks that Betelgeuse still has many thousands of years of life ahead of it and is rather unconcerned by the recent unexpected brightening. "Then you have the next phase that lasts like 10,000 years, then thousands of years, and then it's a century, and the final one is only some days and hours just before the explosion." "The helium-burning phase is several hundred thousand years long," Miguel Montargès, a post-doctoral fellow at the Laboratory of Space Studies and Instrumentation in Astrophysics at the Paris Observatory and Betelgeuse expert, told. While the hydrogen-burning phase of a star's life can last billions of years, each subsequent phase is shorter and shorter. Here it can be seen through the eyes of the Atacama Large Millimeter/submillimeter Array in Chile. The lumpy Betelgeuse is one of the largest known stars. And when that change happens, the center of the star collapses on itself kind of from the inside out, and then that leads to what we call the core-collapse supernova." "So all of a sudden, rather than a reaction which is releasing tremendous amounts of energy, the center of the star starts to absorb energy. "Adding helium nuclei to an iron atom actually extracts energy rather than gives off energy," said MacLeod. Eventually, the star's core fills with iron. With helium gone, the star will sustain itself by burning carbon and oxygen into neon and magnesium, then burning those into silicon. While a star's regular life ends when it runs out of hydrogen and begins to fuse helium in its core, its expanded life as a red giant lasts beyond the helium-burning stage, explained MacLeod. "That means it's still tens of thousands or maybe a hundred thousand years from exploding, if those models are correct." "Our best models indicate that Betelgeuse is in the stage when it's burning helium to carbon and oxygen in its core," Morgan MacLeod, a postdoctoral fellow in theoretical astrophysics at Harvard University and lead author of a recent study about Betelgeuse's Great Dimming, told. The astronomers that spoke to, however, are tempering the supernova expectations. Its 400-day brightness oscillation period has halved to 200 days and, on top of that, the star now appears to be going through the extra brightening that excites skywatchers. If Betelgeuse were to go boom it would be the nearest supernova explosion in more than 400 years and it would be so bright it would be visible even in daylight.Īlthough Betelgeuse has since recovered its usual brightness, the star has not been quite its old self since the Great Dimming. Betelgeuse's recent antics, the beginning of which date back to 2019, have led some to speculate that the moment of its spectacular death might be near. Astronomers believe the star is now fusing helium into carbon and oxygen, a phase in a star's life that lasts tens to hundreds of thousands of years and precedes the star's demise in a supernova explosion. Since early April, however, the star has climbed to the seventh spot and currently shines at over 140% its "usual" brightness, according to the Twitter account Betelgeuse Status, which tracks the star's behavior.īetelgeuse is a red giant, an enormous star that has burned up all the hydrogen fuel in its core and expanded hundreds of times beyond its original envelope. Some 650 light-years from Earth, Betelgeuse usually ranks as the tenth-brightest star in the night sky. The star in question is Betelgeuse, a huge red-tinged star that sits at the left shoulder of the unmissable constellation Orion.
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