Astronomers kill all the fun, blame dust for Betelgeuse’s dimming

Enlarge / This image is a colour composite made from exposures from the Digitized Sky Survey 2 (DSS2). It shows the area around the red supergiant star Betelgeuse. (credit: ESO/Digitized Sky Survey 2/Davide De Martin.)

Betelgeuse is one of the closest massive stars to Earth. It's also an old star, and it has reached the stage when it glows a dull red and expands, with the hot core only having a tenuous gravitational grip on its outer layers. This combination means that we're actually able to resolve different areas on the star's surface, despite the fact that it resides over 700 light years away.

That ability came in handy late last year when Betelgeuse did something unusual: it dimmed so much that the difference was visible to the naked eye. Telescopes pointed at the giant were able to determine that-rather than a tidy, uniform drop in luminance-Betelgeuse's dimming was unevenly distributed, giving the star an odd, squished shape when viewed from Earth. That raised lots of questions about what was going on with the giant, with some experts speculating that, because of Betelgeuse's size and advanced age, the strange behavior was a sign of a supernova in the making.

Now, an international team of observers is here to throw cold water on the possible explosion. Said researchers were lucky to have the Hubble pointed at Betelgeuse before, during, and after the dimming event. Combined with some timely ground observations, this data indicates a rather mundane reason for the star getting darker: a big burp that formed a cloud of dust near the star.

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