Chandra Release - March 29, 2012

Visual Description: Cassiopeia A

A 2-panel illustration and image of a supernova remnant named Cassiopeia A, or Cas A for short, is displayed. The left panel is an artist’s illustration depicting the star before it exploded, and it is made up of a bright blue and navy texture. The artist’s illustration has a cut out going to the star’s core that is colored like a rainbow and shows a simplified picture of the inner layers of the star that formed Cas A just before it exploded. The concentrations of different elements are represented by different colors: iron in the core (blue), overlaid by sulfur and silicon (green), then magnesium, neon and oxygen (red). The right panel shows an X-ray image from NASA’s Chandra X-ray Observatory of the resulting supernova remnant. In this view, the remnant appears as a large, irregularly shaped and patchy cloud, with some areas appearing brighter than others and some areas looking pixellated.   The Chandra image uses the same color scheme as the illustration to show the distribution of iron, sulfur and magnesium in the supernova remnant, with patches of red, green, blue and yellow. The data show that the distributions of sulfur and silicon are similar, as are the distributions of magnesium and neon. Oxygen, which according to theoretical models is the most abundant element in the remnant, is difficult to detect because the X-ray emission characteristic of oxygen ions is strongly absorbed by gas along the line of sight to Cas A, and because almost all the oxygen ions have had all their electrons stripped away.