Quirks & Quarks

A large star that pulled a disappearing act may be a new kind of 'blinking giant'

The giant red stars likely have a binary companion with a large disc that eclipses the star over a period of months.

The giant red stars likely have a binary companion with a large disc that eclipses the star

This 'blinking giant' star was recently found in the brightest part of the Milky Way. Its as yet unidentified companion was whimsically described as a 'giant, hairy, space potato' (Submitted by Philip Lucas)

Astrophysocist Philip Lucas, a professor of astrophysics from the University of Hertfordshire, and his colleagues have identified what they believe to be one of a new class of star. It is called a 'blinking giant' and it is located in the brightest part of our Milky Way Galaxy, approximately 25,000 light years.

In 2012, the giant star, which is 100 times the size of our sun, mysteriously dimmed to nearly nothing for several months after many years of stability.

A new study concluded that the likely explanation is that it is being orbited at some distance by an unidentified companion surrounded by a large opaque disk of gas and dust. That companion — thought to be either a star, a planet or even a black hole — eclipsed the blinking giant.  

Whatever it is, the separation between the two is 20 times that of the Earth from the Sun, which explains the long period for the "blink." 

The Milky Way may be home to many more 'blinking giants' (NASA)

No longer a 'boring' star

Lucas thinks that the star is representative of a new class of blinking giant binary star system. In more conventional binary star systems, one star can eclipse another, sometimes over a period of mere hours. But the timeline of this binary system is very different.

Lucas described the star as being ordinary, even 'boring' to astronomers until it began it's disappearing act. During the eclipse, the blinking giant star became 97 percent fainter. 

More 'blinking giants' out there

Lucas and his colleagues initially thought that this might have been a random occurrence, with some wandering objecct obscuring the star, but now believe that is not the case. This blinking giant has a companion in a regular but very long orbit. There are two other known blinking giants that experience unusually long periods between eclipses.

A star called Epsilon is 50 per cent eclipsed by a huge cloud of dust every 27 years, and there is another star that is eclipsed every 69 years. So far Lucas says astronomers think they have identified as many as six stars as blinking giants like this one, but very likely they will find many more.

Written and produced by Mark Crawley

 

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