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Session 73 - White Dwarfs, Neutron Stars and Pulsars.
Display session, Thursday, June 13
Great Hall,

[73.05] Detection of High Speed Knots in the Compact Nebula of the Vela Pulsar

C. Markwardt, H. Ogelman (UW--Madison)

We report on a sequence of five ROSAT High Resolution Imager observations of the Vela pulsar which spans the two years from May, 1994 to April, 1996. In addition to the detection of the previously-known \sim2 arcmin diameter compact nebula which surrounds the pulsar, we also find curious faint ``knots'' of X-ray emission approximately 15-20 arcsec in diameter. At least one of the knots appears to change position between observations, with an apparent proper motion of 25 arcsec yr^-1, corresponding to a transverse speed of \sim 0.2c if the pulsar is at a distance of 500 pc. The shape of the nebula appears to change over time as well. While it is unclear whether the perceived motion may be due to mass motion or the propagation of an excitational wave, the compact nebula of the pulsar is undoubtedly a violent and turbulent region. We present an animation of the images and our interpretation of the motion.

Program listing for Thursday