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"
In the Center of the Keyhole Nebula
21/07/1997
Stars, like people, do not always go gentle into that good night. The above Keyhole Nebula results from dying star Eta Carinae's violently casting off dust and gas during its final centuries. Eta Carinae is many times more massive than our own Sun, and should eventually undergo a tremendous supernova explosion. Eta Carinae emits much light in colors outside the human visible range. This past week, X-ray emission from Eta Carinae was verified by the orbiting Rossi X-Ray Timing Explorer to be periodic, peaking every 85.1 days. This, along with a previously hypothesized 5.52 year period, indicates that the dying star might be part of a multiple star system.