Stars may twinkle, but they don’t just vanish—so when a distant, giant star pulled a disappearing act for about 200 days, it took astronomers by surprise.
Now, roughly a decade later, astronomers have sifted through a variety of possible explanations—and they still have no idea what’s responsible for blotting out nearly all of the star’s light.
Described in a new study in the Monthly Notices of the Royal Astronomical Society, some of the theories still on the table rely on as-yet unobserved phenomena, such as a dark disk of material orbiting a nearby black hole, or undiscovered, dust-enshrouded companion stars. But over 17 years of observations, the star has only gone dark once, in 2012, making it more difficult for teams to nail down a plausible culprit.
It’s clear that whatever object eclipsed the distant star is huge—much bigger than the star itself. It also appeared to be completely opaque, blocking much of the starlight entirely, and it seemed to have a hard edge.
“The degree of drop in brightness is really impressive,” says Emily Levesque of the University of Washington, who studies massive stars and wasn’t involved in the observations. “It'll be cool to see more observations of this star, of whatever caused this, and to piece together how something like this happened.”
The galaxy is full of weirdly behaving stars, many of which naturally fluctuate in brightness. One of these variable stars, named Betelgeuse, dramatically dimmed in 2019, sparking speculation that it might be...