ocr: PULSAR Ar rapidly rotating neutron star with a mass comparable to that of the Sun's, but collapsed into a sphere about 20 km across. Pulsars are divided into slow second pulsars and fast millisecond pulsars according to their speed of rotation. The latter are former double pulsars that have eaten' their partners and thus gained their huge speed of rotation. Pulsars are like beacons sending out regular flashes of electromagnetic radia- tion, varying from short-waved X rays to radio trequencies. Pulsars result from supernova explosions. The first pulsar, emiffing on radio frequencies, was discov ...
