AAS 197, January 2001
Session 82. Supernova Remnants: Multispectral Observations
Display, Wednesday, January 10, 2001, 9:30am-7:00pm, Exhibit Hall

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[82.15] Hubble Space Telescope WFPC-2 Imaging of Cassiopeia A

J. Morse (University of Colorado-CASA), R. Fesen (Dartmouth College), R. Chevalier (University of Virginia), S. van den Bergh (Dominion Astrophysical Obs), K. Borkowski (North Carolina State University), S. Lawrence (Columbia University)

We observed the young, oxygen-rich supernova remnant Cas A with the HST WFPC-2 through broad filters that capture the total velocity range of the ejecta. The primary ejecta emission lines observed were [OIII]4959,5007 (F450W), [SII]6724+[OII]7325 (F675W), and [SIII]9069,9532 (F950LP). The 4 arcminute diameter main shell of the remnant was covered using 6 WFPC-2 pointings with the F657W filter, and most of this area was covered in 3 pointings with the F450W and F850LP filters. Astonishing structure is observed in the shocked ejecta, where clear examples of Rayleigh-Taylor and cooling instabilities dominate the morphology. Ionization gradients and chemical fractionation within and between filaments are also observed. These data will be used with future (Cycle 10) images to measure precise proper motions in the ejecta to explore the dynamics over large and small scales.

This research was supported by HST/STScI guest observer grants GO-07340.01-96A and GO-08281.02-97A to the University of Colorado and GO-08281.01-97A to Dartmouth College.

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