The end of the mystery! Explanation of the change in brightness of the star Betelgeuse

The mystery of the tarnishing of the star Betelgeuse seems to have officially come to an end. The red supergiant, one of the brightest stars in the night sky and part of the constellation Orion, caught the attention of astronomers around the world in 2019 and was expected to a supernova is about to explode… This was not the case, and now we know what really happened: it was covered in dust created by the star itself.

At that time, some there were hypotheses about the brightness of BetelgeuseSome look at the cooling of the star’s surface, while others look at the giant cloud of gas and dust it has thrown in our direction. In fact, this possible ejection of matter is common for red giants, even long before they are about to explode. However, according to new research, both ideas – cooling and dust – turned out to be correct.

The above animation combines four images of a red supergiant star – the first taken in January 2019, another in December of the same year, and then in January 2020 and March 2020. All images were captured with the SPHERE instrument on the Very Large Telescope. The study was published Wednesday (16) in the journal Nature and shows how the dust cover formed and covered the star.

On the surface of Betelgeuse, some gas bubbles tend to form and move, contract and enlarge, resulting in a change in the star’s temperature. At some point, before the mysterious change in brightness, the star ejected a huge bubble of gas, which retired and then cooled due to the drop in temperature at the star’s surface. This was enough for the ejected gas to condense into solid dust.

Thus, a cloud of dust covered part of the star, which to us looked like a strange decrease in brightness. “We are directly observing the formation of what is called stardust,” said Montarge, one of the study’s authors. “Dust ejected from cold formed stars, such as the ejection we saw, could be the building blocks of terrestrial planets and life,” adds Emily Cannon, who also participated in the study.

This result may not be as exciting as an impending supernova, but it gives scientists relevant information about stardust, and also shows that it is forming very quickly and close to the surface of the star. Betelgeuse will explode sooner or later, but it can take many years for this to happen… Of course, it’s always good to be on the alert, but if we want to witness a supernova it might be better. pay more attention to Eta Carinae, a binary system that is already in the process of erupting.

A source: WHAT