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H.A. Van Tassell, J.J. Hester (ASU), A. Szentgyorgyi (CfA), R. Sankrit (Johns Hopkins)
The observation of a skin of [OIII] \lambda 5007Å emission around the edge of the visible Crab supernova remnant has been explained as a cooling region behind a radiative shock, driven by synchrotron pressure and sweeping up freely expanding ejecta from the original supernova explosion (Sankrit & Hester 1997). Higher ioization species such as [NeV] \lambda3426Åprovide an opportunity for tracing shocks with velocities in excess of about 170 km/s. With recent observations of [NeV] in the southern portion of the remnant (Van Tassell et.al. 1998), little doubt is left about the existence of a shock, and the production of high ionization line emission in the cooling region behind it. Shock parameters such as the shock velocity are constrained by observations covering a wide range of ionizations and excitations. We are presenting images of the entire remnant in emission from [NeV] \lambda3426Å, and compare these with observations in [OIII] \lambda5007Å, [SII] \lambda6717Å& \lambda6734Å, and H\alpha, and with spectra of select locations. Images of the Crab in narrowband filters were taken this winter at the Steward 2.3 meter telescope on Kitt Peak. The images show [NeV] emission spatially exterior to the [OIII] emission, and relatively stronger at the boundary of the nebula than in the filaments. Spectra for the Crab were taken throughout December and January of 1998 and 1999 using the B&C Spectrograph at the Steward 2.3 meter telescope on Kitt Peak. Preliminary analysis of these data are presented, and their implications as to shock properties are discussed. Partial funding for this project was provided by a NASA Space Grant, and by NASA support of the WFPC2 IDT.
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