An international team of astronomers has spotted a giant ‘blinking’ star near the heart of the Milky Way galaxy, more than 25,000 light years away from Earth. The team has observed the star, named VVV-WIT-08, decreasing in brightness by a factor of 30 so that it nearly disappeared from the sky. It is exceptionally rare for a star to become fainter over a period of several months and then brighten again.
The researchers believe that the star may belong to a new class of ‘blinking giant’ binary star system, where a giant star — 100 times larger than the Sun — is eclipsed once every few decades by an as-yet-unseen orbital companion. The companion, which may be another star or a planet, is surrounded by an opaque disc, which covers the giant star, causing it to disappear and reappear in the sky.
The news about the discovery is published in Monthly Notices of the Royal Astronomical Society. The research, which highlighted the ‘blinking’ star, was led by Dr Leigh Smith from Cambridge’s Institute of Astronomy. He worked with scientists at the University of Edinburgh, the University of Hertfordshire, the University of Warsaw in Poland and Universidad Andres Bello in Chile.
Co-author Dr Sergey Koposov from the University of Edinburgh said, “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.”
Since the star is located in a dense region of the milky way, the astronomers considered whether some unknown dark object could have simply drifted in front of the giant star by chance.
Other star systems of the same sort
One other star system of this sort has been known for a long time. The giant star Epsilon Aurigae is partly eclipsed by a huge disc of dust every 27 years but only dims by about 50%. A second example, TYC 2505-672-1, was found a few years ago and holds the current record for the eclipsing binary star system with the longest orbital period — 69 years — a record for which VVV-WIT-08 is currently a contender.
The UK-based team has also found two more of these peculiar giant stars in addition to VVV-WIT-08, suggesting that these may be a new class of ‘blinking giant’ stars for astronomers to investigate.
