Supernova
A supernova is the explosive death of a star, during which it rapidly ejects most of its mass in a brilliant burst of light. In core‑collapse supernovae (Types Ib, Ic, II), massive stars (≥ 8 solar masses) exhaust their nuclear fuel, collapse under gravity, and explode. In Type Ia supernovae, a white dwarf in a binary system undergoes runaway fusion after accreting mass. These events deliver heavy elements into space, leave behind neutron stars or black holes, and power typical shock‑front supernova remnants.
Source: heasarc.gsfc.nasa.gov
APODs including "Supernova"
N132D and the Color of X-Rays
23/05/2002
Supernova remnant N132D shows off complex structures in this sharp, color x-ray image. Still, overall this cosmic debris from a massive star's explosive death has a strikingly simple horseshoe shape. While N132D lies 180,000 light-years distant in the Large Magellanic Cloud, the expanding remnant appears here about 80 light-years across. Light from the supernova blast which created it would have reached planet Earth about 3,000 years ago. Observed by the orbiting Chandra Observatory, N132D still glows in x-rays, its shocked gas heated to millions of degrees Celsius. Since x-rays are invisible, the Chandra x-ray image data are represented in this picture by assigning visible colors to x-rays with different energies. Low energy x-rays are shown as red, medium energy as green, and high energy as blue colors. These color choices make a pleasing picture and they also show the x-rays in the same energy order as visible light photons, which range from low to high energies as red, green, and blue.