XRISM Finds Chlorine, Potassium in Cas A

This composite image of the Cassiopeia A (or Cas A) supernova remnant, released Jan. 8, 2024, contains X-rays from Chandra (blue), infrared data from Webb (red, green, blue), and optical data from Hubble (red and white). A study by the XRISM (X-ray Imaging and Spectroscopy Mission) spacecraft has made the first-ever X-ray detections of chlorine and potassium in the wreckage.