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Something passed in front of a star in a distant part of the Milky Way — but astronomers aren’t sure what’s going on.
Amanda Smith / University of Cambridge
In 2012, a giant star blinked about 25,000 light-years away at Earth, and we stared back, slightly confused.
Astronomers using the VISTA telescope in Chile watched the star dramatically decrease in brightness and then brighten again over the course of about 200 days. The team has a hunch that a large object, orbiting the giant star, briefly obscured our view of it – but the nature of the mysterious object is uncertain. They named it VVV-WIT-08.
“It is amazing that we have just noticed a dark, large, elongated object passing between us and the distant star and we can only speculate what its source is,” said Sergei Koposov, an astronomer at the University of Edinburgh and co-author of a new book. a study.
The study, published in the Monthly Notices of the Royal Astronomical Society, suggests several possibilities, but the dip does not appear to be due to features inherent in the star itself – it must be a gravitationally bound companion.
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The event was discovered in VISTA Variables in a Via Lactea (VVV) survey. WIT is the acronym for “What is this?” It is used when astronomers are not clear about why these giant stars are flashing.
Animation of the mysterious object that passed in front of VVV-WIT-08?
Lee Smith, Sergey Koposov
A number of WIT objects have been discovered before, with a handful of explanations: violent quasars, star collisions, and novas. The team stated that this event is definitely a faint event – something passed in front of the star from our view of the universe – and it should be faint, more than 23 million miles thick (or about a quarter of the distance between the Earth and the sun).
They took into account a number of different things, and ruled out the existence of a shell object wandering in the universe passing in front of the star. It’s also unlikely that the massive disks of debris around white dwarfs and neutron stars caused the disappearance, though the team says a cloud of dusty, chaotic gas and debris around a black hole — a “black hole backup disk” — might be the cause.
The team also identified two other candidate events, VVV-WIT-10 and VVV-WIT-11, suggesting that there may be more “blinking giants” to discover and describe.
“There is certainly more to be found, but the challenge now is to figure out what the hidden companions are, and how they became surrounded by disks, despite orbiting away from the giant star,” Lee Smith, an astronomer at the institute told me. Cambridge Institute of Astronomy and first author of the study.
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