This is the largest yellow hypergiant star ever discovered
Behold HR5171A, a massive yellow star that's an unfathomable 1,300 times the diameter of our sun. It's part of an exotic binary system that was spotted by an international team of astronomers who say it's now among the ten largest stars ever found.
HR5171A just hit the record books for being the largest yellow star we know of. It's 50% larger than the red supergiant Betelgeuse and about one million times brighter than the Sun. It measures a breathtaking 1.2 billion miles (1.8 billion km) in diameter. That's roughly the distance of Saturn to our sun, about 9.6 AU.http://io9.com/this-is-the-largest-yellow-hypergiant-star-ever-discove-1542279399