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The expansion of Cassiopeia A as seen in X-rays

Jacco Vink·Hans Bloemen·Jelle Kaastra·Johan Bleeker
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Abstract

We have for the first time measured the overall expansion rate of the supernova remnant Cas A as seen in X-rays using ROSAT and Einstein HRI images with time differences up to almost 17 years. The overall expansion timescale of Cas A is found to be 501 plusminus 15 yr. This is significantly shorter than the timescale based on high resolution radio data. Although the results clearly indicate that Cas A is not anymore in the free expansion phase,the discrepancy between the radio and X-ray timescales cannot be easily understood. Furthermore, the expansion rate is incompatible with that predicted by a self-similar model for a supernova remnant ploughing through the wind of its progenitor.

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Jacco Vink, Hans Bloemen, Jelle Kaastra, Johan Bleeker. 1998-09-01. The expansion of Cassiopeia A as seen in X-rays. https://arxiv.org/abs/astro-ph/9806319

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