WHY DID A STAR NEARLY VANISH FROM THE SKY?
More than 25,000 light years away, there’s an enormous star that’s 100 times the size of the Sun. It’s in the constellation of Sagittarius, close to the heart of the Milky Way. Yet for about 200 days in 2012, it virtually vanished from the night sky. For those studying stars in this dense region of the galaxy, it was understandably something of a surprise. Astronomers had been working their way through data from the VISTA Variables in the Via Lactea Survey in 2019, but they had certainly not expected to come across anything so perplexing.
What they were witnessing was a dimming on an near-unprecedented scale, with the star, called VVV-WIT-08, decreasing in brightness by a mammoth factor of 30: a staggering 97 per cent. “It’s not particularly unusual for stars to dim by a small amount for short periods,” says Dr Leigh Smith from Cambridge’s Institute of Astronomy. “But it’s very unusual for stars to dim as much and for as long as this.”
Smith led the discovery, working
