Resolved structure in M33 supernova remnants

Abstract

We present WF/PC narrow band forbidden S II 6725-wavelength images of two M33 supernova remnants obtained with the Wide Field/Planetary Camera on the HST. Comparison of these images with ground-based CCD data indicates that HST has resolved the nebular structures into shells or partial shells, permitting improved measurements of the diameters of these objects. Ground-based echelle spectra obtained at Kitt Peak with the 4-m telescope show profiles with half-width zero-intensity velocities of 163 and 275 km/sec for the two objects, indicating rapid bulk motions of the emitting filaments. The morphology of the emission seen in the WF/PC images allows the non-Gaussian shapes of the integrated echelle profiles to be understood. We briefly compare the predicted WF/PC count rates with those actually realized and discuss the reason for the discrepancy.