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Astronomers find 'blinking giant' star at the center of the Milky Way

The newly discovered star VVV-WIT-08 is dimmed by a mystery companion ever few decades. Photo by Amanda Smith/University of Cambridge
The newly discovered star VVV-WIT-08 is dimmed by a mystery companion ever few decades. Photo by Amanda Smith/University of Cambridge

June 11 (UPI) -- Astronomers have discovered a giant, blinking star in the middle of the Milky Way, roughly 25,000 light-years from Earth.

The star's blinking pattern, dimming by a factor of 30, was first identified by the VISTA Variables in the Via Lactea survey, which utilizes the European Southern Observatory's VISTA telescope in Chile.

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Unlike pulsing stars, which brighten and dim across short time-scales, the newly discovered VVV-WIT-08 star -- described Friday in the journal Monthly Notices of the Royal Astronomical Society -- dimmed, nearly disappeared and brightened over a period of months.

Scientists suspect the star won't dim again for a long time.

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In fact, astronomers estimate the VVV-WIT-08 star is member of a new class of "blinking giant" binary star systems, featuring a giant star, 100 times bigger than the sun, and an unidentified companion with a decades-long orbit.

Though scientists don't know whether it's a star or planet, observational data suggests VVV-WIT-08's mystery companion has a large opaque disk that helps block out much of the giant star's light.

"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," study co-author Sergey Koposov, astronomer at the University of Edinburgh, said in a press release.

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Though astronomers don't yet know for certain what's circling VVV-WIT-08, galactic models showed it's highly unlikely that the giant star's light was dimmed by an unrelated passing object.

Astronomers have only a couple of examples of similar binary systems.

The star Epsilon Aurigae is dimmed 50 percent every 27 years by a passing disk of dust.

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And the recently discovered TYC 2505-672-1 is an eclipsing binary star system with an orbital period of 69 years -- a record that could be eclipsed by VVV-WIT-08.

"Occasionally we find variable stars that don't fit into any established category, which we call 'what-is-this?', or 'WIT' objects," project co-leader Philip Lucas said in the release.

"We really don't know how these blinking giants came to be. It's exciting to see such discoveries from VVV after so many years planning and gathering the data," said Lucas, a professor at the University of Hertfordshire.

Ongoing surveys and followup investigations have turned up a number of other blinking giant candidates, but it may be some time before astronomers are able to shed any light on the companions responsible for feature that make these systems unique in the first place -- the blinking.

"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," lead study author Leigh Smith said in a press release.

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"In doing so, we might learn something new about how these kinds of systems evolve," said Smith, a researcher at Cambridge University's Institute of Astronomy.

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