The European Southern Observatory’s Very Large Telescope (VLT) has discovered the largest known yellow hypergiant star – HR 5171 A. It is one of the 10 largest stars now know, measuring 1200 times the diameter of the Sun and one million times brighter.
As another point of comparison, it is 50% larger than the famous red supergiant Betelgeuse.
Located 12,000 light years form Earth, the star HR 5171 A is part of an unusual double star system. Its binary partner is so close to it that the two stars actually touch. Together, the system resembles the shape of a peanut.
Yellow hypergiant stars like HR 5171 A are very rare, with only about 12 known to exist in our Milky way galaxy. Their instability means that they expel materials outwards, forming a glowing atmosphere around the core star.
Read more at ESO.org