binary pulsar

A binary pulsar is a system where one of the stars is a pulsar. Pulsars themselves are rapidly spinning neutron stars, which are incredibly dense remnants of exploded stars. These neutron stars emit beams of radiation from their magnetic poles. As the pulsar spins, these beams sweep across space, and when they pass by Earth, we detect them as regular pulses of radio waves, X-rays, or gamma radiation.12

In a binary pulsar system, the pulsar's intense radiation and the gravitational interactions between the two stars can cause the pulsar to spin faster, especially if it's accreting matter from its companion. The precise timing of these pulses is so accurate that pulsars have been used to test theories of gravity and even detect gravitational waves.213