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Crab Nebula
Crab Nebula diffuse gaseous nebula in the constellation Taurus; cataloged as NGC 1952 and M1, the first object recorded in Charles Messier's catalog of nonstellar objects (see Messier catalog ). It is the remnant of a supernova that was observed in 1054 by Chinese and Arab astronomers to be as bright as Venus; markings in northern New Mexico depict a star near a crescent moon that might be a record of this supernova. Only three other supernovas have been observed in our galaxy since then. The explosion of the Crab Nebula produced a large expanding shell of delicate filaments. The filaments contain ionized gas in which unusually energetic electrons twist through magnetic fields at speeds close to that of light, emitting synchrotron radiation. Although this radiation is what makes supernova remnants visible in radio wavelengths, in this nebula it is so strong that observers can see the filaments through moderate-sized optical telescopes under good conditions. The nebula is also a strong emitter of X rays. At its center is a pulsar , PSR 0531+21, that spins 30 times per second. The youngest pulsar observed, it gives off radiation at radio, optical, ultraviolet, X-ray, and gamma ray wavelengths, as well as electrons that power the synchrotron radiation in the surrounding nebula. |
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"Crab Nebula." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "Crab Nebula." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1E1-CrabNebu.html "Crab Nebula." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-CrabNebu.html |
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Crab Nebula
Crab Nebula A supernova remnant approximately 6500 l.y. away in the constellation Taurus; also known as M1 or NGC 1952, and as the radio source Taurus A. The Crab Nebula is the remains of a star that was seen to explode as a supernova in ad1054, reaching a maximum apparent magnitude of −6. In telescopes it appears as an elliptical nebulosity of 8th magnitude. Its true dimensions are 11 × 7.5 l.y. Optically, the nebula has two components: an outer region of reddish, twisted filaments of hydrogen gas; and an inner, whitish core that shows no spectral features. The light from the core is synchrotron radiation, caused by high-speed electrons from the Crab Pulsar. It is highly polarized and is continuous at all wavelengths, from gamma-rays to radio waves. The expansion velocity of the outer filaments is about 1000 km/s. There is evidence that the expansion is accelerating, driven by the radiation from the pulsar.
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"Crab Nebula." A Dictionary of Astronomy. 1997. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "Crab Nebula." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O80-CrabNebula.html "Crab Nebula." A Dictionary of Astronomy. 1997. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-CrabNebula.html |
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Crab Nebula
Crab Nebula Nebula located c.6500 light years away in the constellation of Taurus. It is the remnant of a supernova noted by Chinese astronomers in July 1054, when it shone as brightly as Venus, visible even in daylight. The nebula was discovered in 1731 by the English astronomer John Bevis, and independently by Charles Messier in 1758.
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"Crab Nebula." World Encyclopedia. 2005. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "Crab Nebula." World Encyclopedia. 2005. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O142-CrabNebula.html "Crab Nebula." World Encyclopedia. 2005. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-CrabNebula.html |
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