A classification scheme for pulsars

Abstract

The implications of a pulsar classification scheme are discussed. Three types of pulsars are distinguished - Type S (S for single) from supernova explosions of single stars; type D (D for disrupted) from binaries disrupted by supernova explosions; and type L (L for liberated) for rejuvenated neutron stars liberated from binaries by supernova explosions. A pulsar can belong to one of two subclasses of D depending on whether the supernova occurred in the more (D1) or less (D2) massive member of the binary. It is suggested that this categorization implies that the age of a type L pulsar is not simply determinable from its spin-down rate. Furthermore, a type L or a type D2 pulsar cannot be assumed to have always been moving with its present velocity, which is the orbital velocity the pulsar had at the time of the disruption of the binary by the second supernova explosion. The reasons for these statements are explained, and the galactic z-distribution of some pulsars is examined.