Wikipedia
A binary pulsar is a pulsar with a binary companion, often a white dwarf or neutron star. (In at least one case, the double pulsar PSR J0737-3039, the companion neutron star is another pulsar as well.) Binary pulsars are one of the few objects which allow physicists to test general relativity because of the strong gravitational fields in their vicinities. Although the binary companion to the pulsar is usually difficult or impossible to observe, the timing of the pulses from the pulsar itself can be measured with extraordinary accuracy by radio telescopes.
Usage examples of "binary pulsar".
I detected weak, rapidly variable, periodic signals from a binary pulsar.
Gravitational lenses and binary pulsar spin-downs reveal general relativity in the depths of space.
Karpal groaned, and flipped to another periodic source, a binary pulsar in Aquila.