And while the planetary folks were busy looking at grains from asteroids, astronomers were using the Hubble Space Telescope to try and understand why some giant stars periodically fade dramatically in brightness. 

We’ve talked to you a lot about Betelgeuse, the red shoulder star of Orion that faded dramatically last year. Well, now another star has got in on the act: VY Canis Majoris. This is a red hypergiant that is 300,000 times brighter than the Sun. This star is actively tossing off its outer atmosphere, and all around it, high-resolution images show the carnage of blasted-off gas and dust. 

In newly published work appearing in The Astronomical Journal with first author Roberta Humphreys, researchers worked to attach ages to the pockets of material moving away from VY Canis Majoris and found that these knots correspond to times when the star dimmed down to 1/6th its usual brightness during the past two centuries. This implies that the release of clouds of dust is a cause for dimming, and this is consistent with many of the theories for why Betelgeuse dimmed. With one explanation seeming to fit the same behavior in two different stars, it is looking more and more like this could be a common explanation for this kind of dimming: dust. It’s a dusty universe, folks.

More Information

NASA Goddard press release

“The Mass-loss History of the Red Hypergiant VY CMa,” Roberta M. Humphreys et al., 2021 February 4, The Astronomical Journal