White dwarfs are believed to be the remnant of a stellar core, after a supernova explosion, which would slowly cool and evaporate as time goes by,
but this theory might be soon scrapped as observations made with the Suzaku X-ray space telescope reveals a new type of white dwarf presenting some strange features that have been associated, in the past, with pulsar activity.

So far, there has been at least one positive discovery of such an object in the AE Aquarii, that seems to present similar behavior to the pulsar situated in the Crab Nebula. The newly discovered white dwarf emits high-energy X-ray radiation while it rotates around its axis, making it the first white dwarf of its kind. Crab Nebula is the remnant debris of a massive supernova explosion of a star at the end of its life.