The distance from the center of a black hole to its event horizon. Pulsars and radio galaxies emit synchrotron radiation. The radiation gets its name because it was first seen in synchrotrons, a type of atomic accelerator. I supernova occurs when the energy released from a collapsing star may be enough to blow the entire star apart. I supernovas leave only a cloud of rapidly expanding gas rich in the leftover carbon and oxygen, plus the silicon, iron, and other elements made during the nuclear burning.
White dwarfs burn no nuclear fuel and shine by residual heat.
They are the end stage of stellar evolution for stars like the Sun. Such systems generally contain a collapsed object such as a neutron star or a black hole. See also x-ray burster. The McGraw-Hill Companies. All rights reserved.