Proper motions of six pulsars

• Published in: Nature (London) 1975-11, Vol.258 (5532), p.215-217
• Main Authors: ANDERSON, B, LYNE, A. G, PECKHAM, R. J
• Format: Article
• Language: English
• Subjects: Humanities and Social Sciences; letter; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/258215a0

SEVERAL authors have suggested that pulsars may be high velocity objects. Prentice 1 found, from a study of the wide distribution of the distances of pulsars to the galactic plane, that their initial velocities may have been as high as 100 km s −1 , and Michel 2 obtained a similar figure for runaway objects formed by the collapse of core fragments in supernova events. Tademaru and Harrison 3 proposed a mechanism for the acceleration of pulsars, by asymmetric radiation, to velocities of 1,000 km s −1 . Only rather meagre direct experimental evidence for high velocities exists, however. This evidence is derived from three different types of observation. First, Lang and Rickett 4 , Galt and Lyne 5 , and Slee et al. 6 have deduced velocities of between ∼ 40 km s −1 and ∼ 600 km s −1 from measurements of the velocity of the interstellar scintillation pattern, found by comparing the scintillation observed at two widely separated stations. These conclusions rely, however, on the pattern being stable in time. In some cases this is clearly not so, and in particular Uscinsci 7 has shown how shear within the scintillating medium can produce an apparent velocity which bears little relation to that of the pulsar. These measurements must therefore be treated with caution. Second, pulse-timing studies by Manchester, Taylor and Van 8 gave an apparent motion of 0.58±0.22″ for PSR1133+16, corresponding to a velocity of 380 km s −1 . Finally, the transverse velocity of the optical object identified with the Crab Nebula pulsar, PSR0531+21, is 100 km s −1 as deduced from the proper motion and estimated distance 9 .