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Crab Nebula: A supernova remnant and pulsar
The Chandra X-ray Observatory produced this X-ray image of the center of the Crab Nebula. The supernova that produced this nebula was seen on Earth in 1054 AD. At the center of the nebula is a rapidly spinning neutron star, or pulsar that emits pulses of radiation 30 times a second. The image shows the central pulsar surrounded by rings of high-energy particles that appear to have been flung outward over a distance of more than a light year from the pulsar. Perpendicular to the rings, jet-like structures produced by high-energy particles blast away from the pulsar. The diameter of the inner ring in the image is about one light year, more than 1000 times the diameter of our solar system. The X rays from the Crab nebula are produced by high-energy particles spiraling around magnetic field lines in the Nebula. The bell-shaped appearance of the Nebula could be due to the way this huge magnetized bubble was produced or to its interaction with clouds of gas and dust in the vicinity.
How does a city-sized neutron star power the vast Crab Nebula? The expulsion of wisps of hot gas at high speeds appears to be at least part of the answer. The movie shows a wisp of gas moving out at about half the speed of light. Wisps like this likely result from tremendous electric voltages created by the central pulsar, a rapidly rotating, magnetized, central neutron star. The hot plasma strikes existing gas, causing it glow in colors across the electromagnetic spectrum.
The inner X-ray ring is thought to be a shock wave that marks the boundary between the surrounding nebula and the flow of matter and antimatter particles from the pulsar. Energetic electrons and positrons (antielectrons) move outward from this ring to brighten the outer ring and produce an extended X-ray glow.
The fingers, loops, and bays in the image all indicate that the magnetic field of the nebula and filaments of cooler matter are controlling the motion of the electrons and positrons. The particles can move rapidly along the magnetic field and travel several light years before radiating away their energy. In contrast, they move much more slowly perpendicular to the magnetic field, and travel only a short distance before losing their energy.
This effect can explain the long, thin, fingers and loops, as well as the sharp boundaries of the bays. The conspicuous dark bays on the lower right and left are likely due to the effects of a toroidal magnetic field that is a relic of the progenitor star.