THE PROPER MOTIONS OF 26-PULSARS

Observations of the proper motion of 26 pulsars have been made using radio interferometry. Comparison with other measurements suggests that proper motion estimates derived from timing observations contain a source of error not accounted for in their quoted uncertainties. Pulsars are seen to have rms space velocities of about 210 km s1. The dis- tribution does not seem to be Maxwellian, there being excesses of both high and low velocity objects. The pulsars are observed to be moving away from the galactic plane, indicating an origin in low z-distance Population I progenitors. The data are compatible with the birth of pulsars in the super- nova events of massive stars, pulsars being the compact neutron star remnants which are given a high velocity during or shortly after the explosion. Although it is found that these measurements of proper motion rule out most of the suggested associations between pulsars and supernova remnants, it is argued that this is not unexpected. The kinetic ages derived by extrapolating the pulsar paths back to the plane are, in general, less than the characteristic ages determined from the spin-down rate. This may be explained by a secular decay of the effective magnetic dipole moment of the pulsars due either to magnetic field decay or alignment of the magnetic and rotation axes on a time-scale of somewhat less than 10 My. ©Royal Astronomical Society.