The Fastest Known Spinning Star Is a Dead One

Dead stars can be extreme in other ways too. The pulsar PSR J1748-2446ad spins 716 times per second, the fastest known, and its equator whips around at up to roughly a quarter of the speed of light. Pulsars like it also blast out streams of charged particles at relativistic speeds. A star spinning that fast can’t be wider than about 32 km, so it has to be a neutron star—a city-sized ball of crushed matter.