At 1,300 times the diameter of our sun (making it an extraordinary 1.1bn miles across) and more than a million times brighter, the yellow hypergiant HR 5171 A is a genuine super star. One of the 10 largest stars yet to be found, it is 12,000 light years from Earth but is sometimes visible to the naked eye. New observations by the European Southern Observatory, in Chile, have revealed a twin.
• This caption was amended on 13 March 2014 because the original said HR 5171 is one of the 10 biggest objects yet to be found in the solar system. The star's full name is HR 5171 A, and it is not in our solar system.
Photograph: AFP/ESO/Digitised Sky Survey 2HR 5171
