Immortalized the cloud that between 2019 and 2020 had made the star Betelgeuse pale and made fear of its imminent explosion. The data published in the journal Nature by the group of Miguel Montarge, of the Paris Observatory, were obtained thanks to the Very Large Telescope (Vlt) of the Southern European Observatory (ESO) and confirm that the cause of that sudden pallor was the ejection of a large mass of gas which, when cooled, obscured the view of the star.
At the end of 2019, the brightness of Betelgeuse, one of the brightest stars, had suddenly dropped. A change visible even to the naked eye and the beginning of a mystery that had also raised concerns about the possibility that this great star, just 400 light years away and with a radius of 1,000 times that of the Sun, was entering its last phase of life and was ready to explode in a supernova.
The variations in the brightness of Betelgeuse photographed by the Vlt Telescope from January 2019 to April 2020 (source: ESO / M. Montargès et al.)
The new images obtained with the powerful Vlt telescope, which is located in the Chilean Atacama desert, now confirm what had already emerged a few months ago thanks to the data of the Hubble Space Telescope: to cause that sudden decrease in brightness was a cloud of dust and gas, which had obscured the view of the star for some time.
Betelgeuse is in a phase of its life cycle in which the outermost layers expand and contract regularly. It may happen that in this process the star may lose part of the outer material, giving rise to gas bubbles that explode and release materials. Just one of these bubbles, at the end of 2019, would have expelled gas that once cooled would have condensed thus obscuring the view of the star.
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