Betelgeuse – a red supergiant located in the constellation Orion – has lost more than two-thirds of its brilliance, raising fears that the star is reaching the end of its life and is about to explode.
Astronomers were left bemused by the discovery, dubbed the “great gradation” at the end of 2019.
But an international team of researchers now believe a cloud of stardust was responsible.
The team came to their conclusion after analyzing images of Betelgeuse over the years using the Very Large Telescope (VLT) at the European Southern Observatory (ESO) in Chile.
They revealed in the scientific journal Nature how the event was triggered by the formation of stardust obscuring half of Betelgeuse.
Miguel Montarges, Paris Observatory, France, and KU Leuven, Belgium, who is the lead author of the study, added: “For once we were seeing the appearance of a star change in real time. on a scale of several weeks.
“We have directly witnessed the formation of what is called stardust. “
But the gradation at Betelgeuse – which is about 500 light years from Earth – only lasted a few months before the star returned to its original lighting level in April 2020.
The star’s surface is subjected to regular changes as giant gas bubbles move, shrink, and swell – in a phenomenon known as pulsation.
Scientists believe Betelgeuse ejected a large gas bubble during gradation.
Soon after, as the star’s surface partially cooled, heavier elements in the gas, like silicon, condensed into solid dust.
Professor Stefan Kraus of the University of Exeter, one of the study’s authors, added: “Aging stars such as Betelgeuse have long been suspected of producing dust spots, either by constant wind or by more localized surface ejections.
“Here we see Betelgeuse ejecting a massive cloud of dust that obscured half of the star’s surface while drifting through space. “
Scientists will continue to examine the star, which is about 1,000 times the size of the sun, to see the ejection of another gas bubble.
Study author and astronomer at the Harvard-Smithsonian Center for Astrophysics in the United States, Andrea Dupree, said the research “affects our understanding of the evolution of all stars.”