X-ray binary

The infalling matter releases gravitational potential energy, up to 30 percent of its rest mass, as X-rays.

The lifetime and the mass-transfer rate in an X-ray binary depends on the evolutionary status of the donor star, the mass ratio between the stellar components, and their orbital separation.

Note that the classification by mass (high, intermediate, low) refers to the optically visible donor, not to the compact X-ray emitting accretor.

[1] The other component, a donor, usually fills its Roche lobe and therefore transfers mass to the compact star.

One of the most famous high-mass X-ray binaries is Cygnus X-1, which was the first identified black hole candidate.

These X-ray pulsars are due to the accretion of matter magnetically funneled into the poles of the compact companion.

With a longer periodicity, a year and beyond, the HMXB can become a double neutron star binary if uninterrupted by a supernova.

Microquasars are named after quasars, as they have some common characteristics: strong and variable radio emission, often resolvable as a pair of radio jets, and an accretion disk surrounding a compact object which is either a black hole or a neutron star.

A part of the radio emission comes from relativistic jets, often showing apparent superluminal motion.