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"
Moving Echoes Around SN 1987A
24/10/1997
Yesterday's image highlighted reflective rings of light emitted by a supernova explosion. Today's pictures, taken over a year apart, highlight how these echoes are seen to move over time. Visible on the left of each picture is part of a reflective ring, an existing dust cloud momentarily illuminated by the light of Supernova 1987A. Note how the nebulosity reflecting the most light occurs farther to the left in the lower photograph. If you look closely, you can see the actual location of SN 1987A itself on the right of each photograph: it appears in the center of a small yellowish ring. The apparent motion and brightness of these echoes help astronomers understand the abundance and distribution of interstellar nebulae in the LMC galaxy, where the stellar explosion occurred.