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Astron. Astrophys. 344, 367-370 (1999)


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A new HST measurement of the Crab Pulsar proper motion *

P.A. Caraveo 1,2 and R.P. Mignani 3

1 Istituto di Fisica Cosmica del CNR, Via Bassini 15, I-20133 Milan, Italy (pat@ifctr.mi.cnr.it)
2 Istituto Astronomico, Via Lancisi 29, I-00161 Rome, Italy
3 STECF-ESO, Karl-Schwarzschild-Strasse 2, D-85740 Garching, Germany (rmignani@eso.org)

Received 27 October 1998 / Accepted 23 December 1998

Abstract

We have used a set of archived HST/WFPC2 exposures of the inner regions of the Crab Nebula to obtain a new measurement of the pulsar proper motion, the first after the original work of Wyckoff & Murray, more than 20 years ago. Our measurement of the pulsar displacement, [FORMULA] mas yr-1, agrees well with the value obtained previously. This is noteworthy, since the data we have used span less than 2 years, as opposed to the 77 years required in the previous work.

With a position angle of [FORMULA], the proper motion vector appears aligned with the axis of symmetry of the inner Crab nebula, as defined by the direction of the X-ray jet observed by ROSAT. Indeed, if the neutron star rotation is to be held responsible both for the X-ray jet and for the observed symmetry, the Crab could provide an example of alignment between spin axis and proper motion.

Key words: stars: pulsars: individual: Crab – astrometry

* Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555

Send offprint requests to: P.A. Caraveo

© European Southern Observatory (ESO) 1999

Online publication: March 10, 1999

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