The X-Ray Expansion of the Supernova Remnant Cassiopeia A
The X-Ray Expansion of the Supernova Remnant Cassiopeia A
We present the first X-ray expansion measurements of the young, bright supernova remnant Cas A. We have acquired a deep (232 ks) ROSAT high-resolution image of Cas A that is compared with archival images of similar quality taken 17 yr earlier with the Einstein Observatory. The average expansion rate between …