brightest X-ray source

The brightest persistent X-ray source in the sky, and also the first to be identified, is known as Scorpius X-1. It was discovered in 1962 by a rocket-borne detector. It was subsequently identified with a star that appears as magnitude 13 in visible light. Its distance is not known with any certainty. Scorpius X-1 is now considered to be a prototype of the low-mass X-ray binaries. One of the pair is a neutron star and the other a fairly normal dwarf star. Material from the normal star is attracted towards the neutron star by its strong gravitational field and forms a disk around it. Energy is released by the material falling towards the neutron star, and it is this energy that is responsible for generating the powerful X-ray emission.