Black Widow Pulsars
Black widows are pulsars (rapidly spinning magnetized neutron stars) that irradiate and gradually devour a companion star. The companion begins its life as a regular main-sequence star (similar to the Sun), and over the course of billions of years it is reduced to only a few percent of its original mass.​
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We showed, in contrast to previous thoughts, that the pulsar's irradiation is too weak to directly evaporate the companion star on its own during its lifetime. Instead, the evaporation causes the companion's orbit to shrink, such that the pulsar's gravity can gradually tear the companion apart in a process called Roche-lobe overflow.​
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Evolutionary tracks of black widow companions that gradually lose their mass m, for different pulsar irradiation strengths L.