* Astronomy

HR 5171 A: VLT Spots Largest Yellow Hypergiant Star

ESO's Very Large Telescope Interferometer has revealed the largest yellow star - and one of the ten largest stars found so far. This hypergiant has been found to measure more than 1300 times the diameter of the Sun, and to be part of a double star system, with the second component so close that it is in contact with the main star. Observations spanning over sixty years, some from amateur observers, also indicate that this rare and remarkable object is changing very rapidly and has been caught during a very brief phase of its life.
Using ESO's Very Large Telescope Interferometer (VLTI), Olivier Chesneau (Observatoire de la Côte d'Azur, Nice, France) and an international team of collaborators have found that the yellow hypergiant star HR 5171 A is absolutely huge - 1300 times the diameter of the Sun and much bigger than was expected. This makes it the largest yellow star known. It is also in the top ten of the largest stars known - 50% larger than the famous red supergiant Betelgeuse - and about one million times brighter than the Sun.
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