Astronomers reveal 'largest yellow star ever'

Astronomers have spotted the largest yellow star ever observed in our galaxy and 1,300 times larger than the sun. The yellow hypergiant star HR 5171 A is also in the top-10 of the largest stars known and about one million times brighter than the sun, Olivier Chesneau, whose team made the discovery, said Wednesday. Despite its great distance of nearly 12,000 light-years from earth, the object can just about be seen with the naked eye. "The new observations also showed that this star has a very close binary partner, which was a real surprise," said Chesneau, of the Observatoire de la Cote d'Azur, in Nice, France. "The two stars are so close that they touch and the whole system resembles a gigantic peanut." His team estimated the star is 50 percent larger than the famous red supergiant Betelgeuse. Yellow hypergiants are very rare, with only a dozen or so known in our galaxy. HR 5171 A has been getting bigger over the last 40 years, cooling as it grows, the astronomers said. Chesneau and an international team used a Very Large Telescope Interferometer (VLTI) of the European Southern Observatory in Paranal, Chile. A technique called interferometry combines light collected from multiple individual telescopes to effectively create a giant telescope up to 140 metres (460 feet) in size.