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physical object > natural object > celestial body > nebula > H II region > gaseous nebula > expanding emission nebula > planetary nebula
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planetary nebula
subjectfact 
planetary nebulahas expansion velocity typically 10 km/s2001-09-27 09:30:11.0
has catalog planetary nebula catalog2001-09-27 09:30:11.0
has definition A bubble of gas surrounding a hot, dying star. The star is so hot that it makes the planetary nebula glow, which allows astronomers to see it. The star was once the core of a red giant, which ejected its outer atmosphere and created the planetary. A planetary nebula has nothing to do with a planet, but through a small telescope, it looks like a planet's disk, hence the misleading name.has source: Croswell, K. 1995 The Alchemy of the Heavens, Anchor Books, 2001-09-27 09:30:11.0
has definition An expanding envelope of rarefied ionized gas surrounding a hot white dwarf. The envelope receives ultraviolet radiation from the central star and reemits it as visible light by the process of fluorescence. The planetary nebula stage lasts for less than 50,000 years. During the core contraction that terminates the red-giant stage, the helium-burning shell is ejected at a velocity so high that it becomes separated from the core. Under current theories, a star with a carbon core and a mass greater than 0.6 Msun (but less than 4 Msun) will become a planetary nebula and leave behind a white dwarf. Planetary nebulae are now known to occur in stars less than 4 Msun whose envelope becomes unstable during the hydrogen shell burning stage.has source: Hopkins, J. 1976 Glossary of Astronomy and Astrophysics, University of Chicago Press, 2001-09-27 09:30:11.0
is a kind of expanding emission nebula2001-09-27 09:30:11.0
expanding emission nebulahas composition enhanced with heavy elements relative to the interstellar medium2001-09-27 09:30:11.0
has explosion date2001-09-27 09:30:11.0
has progenitor star2001-09-27 09:30:11.0
gaseous nebulahas synonym emission nebula2001-09-27 09:30:11.0
nebulais a part of gas2001-09-27 09:32:19.0
celestial bodyhas spectra2001-09-27 09:30:09.0
physical objecthas location or center of gravity2001-09-27 09:27:27.0
has angular momentum2001-09-27 09:27:27.0
has mass2001-09-27 09:27:27.0
has velocity2001-09-27 09:27:27.0
has momentum2001-09-27 09:27:27.0
has temperature2001-09-27 09:27:27.0
has volume2001-09-27 09:27:27.0
has extent2001-09-27 09:27:27.0
has material2001-09-27 09:27:27.0

Kinds of planetary nebula :

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