Detail of the southeastern region of Cas A as imaged by the Chandra X-Ray Observatory in 2000 January. The spectral extraction regions used for the linear series of compact Fe-rich knots (circles, starting from the center moving outward) and the extremely Fe-rich cloud (box) are marked. On the right is the Chandra image of roughly the same region, but including only the photons in the Fe L energy range; superposed are contours showing Fe L line-to-continuum ratios.
