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Session 75 - The Crab Nebula.
Display session, Thursday, June 13
We present results of an extensive study of the structure, morphology and motion of the outer Crab Nebula. New observations with the Hubble Space Telescope over an eight-month baseline reveal visible propagation of features through the body of the outer Crab synchrotron nebula. The features, which have a characteristic width of around 1" in the outer parts of the nebula, are seen to propagate from the very inner regions out to close to the edge of the nebula. The probable physical nature of these waves is discussed in an accompanying paper (Hester et al, this session). Dramatic animation sequences are presented depicting the wave motion in the outer nebula. This motion is seen most easily against static structures, provided conveniently in the form of dark, dusty filament cores seen in projection against the bright continuum emission.
To gain a better insight into this field structure, we also present deep ground-based imaging polarimetric observations that provide maps of the polarized emission. By isolating sharp features in the polarized images and subtracting off the background we are able to show that the magnetic field runs along surface brightness features throughout the nebula, confirming the interpretaton of these featues as flux tubes. High pass filtered versions of the HST images also reveal a wealth of magnetic structure within the nebula, including structure "draping" over the jet to the SE of the pulsar, similar to that reported by Hester et al (1995, ApJ, 448, 240) draping over the counterjet to the NW of the pulsar.
Program listing for Thursday