Astronomers have spotted a rare “blinking” star that is 100 times the size of the sun, located more than 25,000 light years away, near the centre of the galaxy. Observed by an international team of researchers, the giant star (named VVV-WIT-08) dimmed by 97 per cent over the course of a few hundred days, almost disappearing from the sky, then slowly returned to its usual brightness.
Scientists aren’t entirely sure what caused the phenomenon — WIT stands for “what is this”, a moniker for variable stars that don’t fit into an established category — but suggest that it’s most likely to be the result of a large, as-yet-undiscovered object in the star’s orbit, such as a planet or companion star surrounded by a disc of opaque dust.
Initially, researchers also considered the possibility that the star was dimmed by a massive dark object passing by and obscuring it by chance, as it resides in a densely-populated region of the Milky Way. However, simulations revealed that there would need to be an implausibly large amount of dark objects floating around the galaxy for this theory to check out.
“It’s amazing that we just observed a dark, large, and elongated object pass between us and the distant star and we can only speculate what its origin is,” says the University of Edinburgh’s Dr. Sergey Koposov, who co-authored the study published in the Monthly Notices of the Royal Astronomical Society.
The star was found via data gathered by the Chile-based Vista telescope as part of the VISTA Variables in the Via Lactea survey (VVV). This telescope has been watching the same billion stars for almost a decade, searching for stars with varying brightness on the infrared spectrum. It was also observed by the University of Warsaw’s Optical Gravitational Lensing Experiment (OGLE), which makes observations closer to the visible spectrum.
VVV-WIT-08 isn’t alone, though. Astronomers have now identified around half a dozen potential binary star systems of the same variety, and they are sure that there are more “blinking giants” out there still to be discovered.
“There are certainly more to be found, but the challenge now is in figuring out what the hidden companions are, and how they came to be surrounded by discs, despite orbiting so far from the giant star,” says the leader of the discovery team, Dr. Leigh Smith. “Once you start to build up collections of several of these things, you can look at their properties in aggregate and unpick the mysteries of where these discs come from.”
Watch a simulation of the VVV-WIT-08 star system in action below.