Crab Nebula

X-ray Emission from the Crab Nebula

The Crab Nebula is a large cloud of gas which was produced a stellar explosion that was seen in AD 1054. The nebula is 6000 light years from Earth, so the explosion observed in AD 1054 actually occurred 6000 years earlier. Stars with masses of more than 10 times the sun's mass are thought to end their lives in great cataclysmic explosions called supernovae. When a supernova occurs, most of the material which comprises the star gets thrown out into space. The small core of the star (typically a sphere of about 10 km in radius) may remain behind as an ultradense "compact object", generally a neutron star, but sometimes, in extreme cases, a black hole. In the case of the Crab Nebula, we can see both the nebula and the neutron star. The neutron star spins very rapidly, about 30 times per second.

X-ray emission from the Crab Nebula allows us to probe the ejected outer material, along with the regions nearest the neutron star. The images above show 3 views of the crab nebula; the image on the left was obtained by the high resolution imager on the ROSAT X-ray observatory, while the middle image is the ROSAT HRI image represented as a 3-D surface. These images show the bright point-like emission associated with the neutron star, along with emission from material farther out. The recent Chandra X-ray observatory image represents the best view of the X-ray emission from the Crab ever obtained. The Chandra image shows tilted rings or waves of high-energy particles that appear to have been flung outward over the distance of a light year from the central star, and high-energy jets of particles blasting away from the neutron star in a direction perpendicular to the spiral.

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Page Author: Dr. Michael F. Corcoran
Last modified May 26, 2001