Artist's impression of an X-ray binary. These binary star systems comprise a compact star (neutron star or, as here, a black hole) which is in orbit about a larger companion (in this case, a blue giant). The compact star distorts the companion and pulls gas from its atmosphere. The gas swirls around the compact object forming an accretion disc. Particle jets are sometimes emitted from the centre of this disc, making the systems superficially similar to the much larger and totally different quasars.