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Supernova remnant is what's left from a supernova.
Supernova remnant is the structure resulting from the gigantic explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave. The supernova remnant consists of ejected material expanding from the explosion of the supernova, and the interstellar material it sweeps up and shocks along the way.
There are two possible 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 1% the speed of light, some 3,000 km/s. When this material collides with the surrounding circumstellar or interstellar gas, it forms a shock wave that can heat the gas up to temperatures as high as 10 million K, forming a plasma.
Perhaps the most famous and best-observed young SNR was formed by SN 1987A, a supernova in the Large Magellanic Cloud that was discovered in 1987. Other well-known, older, supernova remnants include Tycho (SN 1572), a remnant named after Tycho Brahe, who recorded the brightness of its original explosion (AD 1572) and Kepler (SN 1604), named after Johannes Kepler. The most recent remnant in our galaxy is G1.9+0.3, discovered in the galactic center and estimated to have gone supernova 140 years ago.
Supernova remnant passes through the following stages as it expands:
Types of supernova remnant. There are three types of supernova remnant:
Supernova remnants: Origin of cosmic rays.
Supernova remnants are considered the major source of galactic cosmic rays. The connection between cosmic rays and supernovas was first suggested by Walter Baade and Fritz Zwicky in 1934. Vitaly Ginzburg and Sergei Syrovatskii in 1964 remarked that if the efficiency of cosmic ray acceleration in supernova remnants is about 10 percent, the cosmic ray losses of the Milky Way are compensated. This hypothesis is supported by a specific mechanism called "shock wave acceleration" based on Enrico Fermi's ideas, which is still under development.
Indeed, Enrico Fermi proposed in 1949 a model for the acceleration of cosmic rays through particle collisions with magnetic clouds in the interstellar medium. This process, known as the "Second Order Fermi Mechanism", increases particle energy during head-on collisions, resulting in a steady gain in energy. A later model to produce Fermi Acceleration was generated by a powerful shock front moving through space. Particles that repeatedly cross the front of the shock can gain significant increases in energy. This became known as the "First Order Fermi Mechanism".
Supernova remnants can provide the energetic shock fronts required to generate ultra-high energy cosmic rays. Observation of the SN 1006 remnant in the X-ray has shown synchrotron emission consistent with it being a source of cosmic rays. However, for energies higher than about 1015 eV a different mechanism is required as supernova remnants cannot provide sufficient energy
External links for supernova remnants...
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