PSR B1957+20, also known as the Black Widow Pulsar, is a pulsar discovered in 1988 about 4,500 light-years away from Earth. Around it is a former companion star that has been eroded to a substellar mass by the pulsar wind, which was among the first extrasolar substellar objects discovered. Many other similar systems have since been discovered, which are referred to as "black widow" pulsars after this system.
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