A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way.
SN 1054 remnant (Crab Nebula).
HBH 3 (Spitzer Space Telescope; August 2, 2018)
G54.1+0.3 (November 16, 2018)
Image: 15 044a Super Nova Remnant Planet Formation SOFIA 20150319
A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
SN 1994D (bright spot on the lower left), a type Ia supernova within its host galaxy, NGC 4526
The Crab Nebula is a pulsar wind nebula associated with the 1054 supernova.
A 1414 text cites a 1055 report: since "the baleful star appeared, a full year has passed and until now its brilliance has not faded".
2015 supernova in galaxy cluster RXC J0949.8+1707. In 2011, two supernovae were observed in the same face-on spiral galaxy.
