06 February 2020, The Tablet

Look on the bright side


Across the Universe

Look on the bright side
 

Betelgeuse, the bright red star in Orion whose dimming I wrote about last month, is not the only star in the sky undergoing visible changes. As I mentioned then, many stars are known to vary in brightness. One such star, V Sagittae, is an example of a “cataclysmic variable”: actually a pair of orbiting stars, one ordinary and one a white dwarf. On occasion, some of the gas from the ordinary star is pulled on to the white dwarf, causing it to flare up.

At an astronomy conference in January, researchers at Louisiana State University described how this particular pair is not only flickering in brightness but actually growing in brightness over many years. Using both the reports to the American Association of Variable Star Observers and measurements of the star’s intensity on glass plate photographs stored at the Harvard College Observatory from as far back as the late nineteenth century, they were able to measure just how rapidly it is getting brighter. It’s already 10 times brighter now than it was in 1890.

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