Wiktionary
n. (context astronomy English) A nebula that is formed from supernova explosion debris.
Wikipedia
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.
There are two common routes to a supernova: either a massive star may run out of fuel, ceasing to generate fusion energy in its core, and collapsing inward under the force of its own gravity to form a neutron star or a black hole; or a white dwarf star may accumulate ( accrete) material from a companion star until it reaches a critical mass and undergoes a thermonuclear explosion.
In either case, the resulting supernova explosion expels much or all of the stellar material with velocities as much as 10% the speed of light, that is, about 30,000 km/s. These ejecta are highly supersonic: assuming a typical temperature of the interstellar medium of 10,000 K, the Mach number can initially be > 1000. Therefore, a strong shock wave forms ahead of the ejecta, that heats the upstream plasma up to temperatures well above millions of K. The shock continuously slows down over time as it sweeps up the ambient medium, but it can expand over hundreds or thousands of years and over tens of parsecs before its speed falls below the local sound speed.
One of the best observed young supernova remnants was formed by SN 1987A, a supernova in the Large Magellanic Cloud that was observed in February 1987. Other well-known supernova remnants include the Crab Nebula, Tycho, the remnant of SN 1572, named after Tycho Brahe who recorded the brightness of its original explosion, and Kepler, the remnant of SN 1604, named after Johannes Kepler. The youngest known remnant in our galaxy is G1.9+0.3, discovered in the galactic center.
Usage examples of "supernova remnant".
A collapsed supernova remnant: very small, very hot, very dense, the mass of the sun crammed into the volume of a city block.
The gloom deepened as the pale supernova remnant was eclipsed by the edge of the ceiling.
Then it would rouse itself for one final frantic spell of recording and transmission before plunging to its immolation in the turbulent supernova remnant of Alpha Centauri.
He imagined how the ship must look from space, her bright side bronzed, her shadowed side sheened a deep vibrant blue by the fainter but hotter filaments of the supernova remnant, which was now flung over the equivalent of some four arc-minutes of sky, and seemed to fill everything from zenith to nadir.
The ultimate collapsar, a supernova remnant so massive that its gravitational force upon itself compressed it to a smallness, a field strength, such that light could no longer escape.
It was a gigantic supernova remnant, a shock front from the death of a star over a million years in the past.
It is not an amoeba at all, not an explosion of dust, not a supernova remnant, but a—.
It is not an amoeba at all, not an explosion of dust, not a supernova remnant, but a&mdash.
It is not an amoeba at all, not an explosion of dust, not a supernova remnant, but a-remarkable!
It is not an amoeba at all, not an explosion of dust, not a supernova remnant, but a -- remarkable!
Except only for a nearby supernova remnant in Cassiopeia, it was the brightest radio source in the sides of Earth.
Abandoned Heechee base, supernova remnant, planet stripped bare by some other intelligent racethe destination could be anything at all.