A type 1a supernova occurs when a white dwarf grows too heavy with material pulled from a nearby star, becomes unstable, and explodes in a gargantuan thermonuclear reaction. The aftermath of such an event is what we see in this Chandra Observatory image of the X-ray emitting gas bubble (colored aqua-blue and lavender) known as DEM L71. The sharp outer shell is an outward-propagating shock wave, while the light-blue inner portion is iron and silicon gas. The remnant's two distinct pieces allowed scientists to directly determine the temperature of the inner cloud at ten million degrees Celsius.
For more information, see the press release from the Chandra X-Ray Observatory.