At the centre of every large galaxy lives a giant black hole that swallows gas or dust clouds that stray too close. As matter spirals inwards, it is compressed into an accretion disk. By the time it falls into the black hole, the matter is so hot that much of its mass is converted to energy, which emerges as heat, light and jets of high-energy particles. http://www.nature.com/polopoly_fs/7.14928.1389717382!/image/Quasar.jpg_gen/derivatives/landscape_630/Quasar.jpg
Scientists have discovered the first binary system ever known to consist of a black hole and a ‘spinning’ star – or more accurately, a Be-type star. Although predicted by theory, none had previously been found.