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T. DeLaney (CfA), J. D. Smith (U. of Arizona), L. Rudnick, J. Ennis (U. of Minnesota), W. Reach, J. Rho (SSC), T. Kozasa (Hokkaido U.), H. Gomez (Cardiff U.)
We present Doppler velocity images of the young supernova remnant Cassiopeia A in the infrared emission lines of Ar, Ne, Si, and S observed with the Spitzer IRS and covering nearly the whole extent of the remnant. We identify many of the same structures mapped with optical spectroscopy including red- and blue-shifted rings of emission to the north and blue-shifted "parentheses" structures just southeast of the remnant center. The measured infrared velocities are consistent with the optical velocities and range between ± 6000 km/s. To the south we identify a red-shifted Ne structure that has no bright optical or X-ray counterpart. There is also bright Ne emission in the blue-shifted ring to the north, perhaps suggesting a bi-directional outflow of Ne-rich ejecta. The Si and S emission near the center of the remnant, that is possibly associated with ejecta that have not yet encountered the reverse shock, also shows both red- and blue-shifted structures with velocities between ± 2000 km/s. This work was performed for the Jet Propulsion Laboratory, California Institute of Technology, sponsored by the United States Government under Prime Contract between California Institute of Technology and NASA.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.