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"
Simeis 147: Supernova Remnant
31/01/2009
It's easy to get lost following the intricate filaments in this detailed image of faint supernova remnant Simeis 147. Also cataloged as Sh2-240 and seen towards the constellation Taurus, it covers nearly 3 degrees (6 full moons) on the sky. That corresponds to a width of 150 light-years at the stellar debris cloud's estimated distance of 3,000 light-years. The remarkable narrow-band composite image in the Hubble color palette includes emission from hydrogen, sulfur, and oxygen atoms tracing regions of shocked, glowing gas. This supernova remnant has an estimated age of about 40,000 years - meaning light from the massive stellar explosion first reached Earth 40,000 years ago. But this expanding remnant is not the only aftermath. The cosmic catastrophe also left behind a spinning neutron star or pulsar, all that remains of the original star's core.