Definitions for planetary nebula
plan·e·ta·ry neb·u·la

Princeton's WordNetRate this definition:0.0 / 0 votes

1. planetary nebulanoun

   a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star

WiktionaryRate this definition:0.0 / 0 votes

1. planetary nebulanoun

   A nebulosity surrounding a dying star, consisting of material expelled by the star.

2. Etymology: Coined by William Herschel because of their apparent resemblance to the planet Uranus.

WikipediaRate this definition:0.0 / 0 votes

1. Planetary nebula

   A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.The term "planetary nebula" is a misnomer because they are unrelated to planets. The term originates from the planet-like round shape of these nebulae observed by astronomers through early telescopes. The first usage may have occurred during the 1780s with the English astronomer William Herschel who described these nebulae as resembling planets; however, as early as January 1779, the French astronomer Antoine Darquier de Pellepoix described in his observations of the Ring Nebula, "very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". Though the modern interpretation is different, the old term is still used. All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula at the end of its life cycle. They are relatively short-lived phenomena, lasting perhaps a few tens of millennia, compared to considerably longer phases of stellar evolution. Once all of the red giant's atmosphere has been dissipated, energetic ultraviolet radiation from the exposed hot luminous core, called a planetary nebula nucleus (P.N.N.), ionizes the ejected material. Absorbed ultraviolet light then energizes the shell of nebulous gas around the central star, causing it to appear as a brightly coloured planetary nebula. Planetary nebulae probably play a crucial role in the chemical evolution of the Milky Way by expelling elements into the interstellar medium from stars where those elements were created. Planetary nebulae are observed in more distant galaxies, yielding useful information about their chemical abundances. Starting from the 1990s, Hubble Space Telescope images revealed that many planetary nebulae have extremely complex and varied morphologies. About one-fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms that produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may play a role.

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1. planetary nebula

   A planetary nebula is a kind of emission nebula consisting of an expanding, luminous shell of ionized gas ejected from old red giant stars late in their lives. They are relatively short-lived phenomena, lasting a few tens of thousands of years, compared to the typically longer than a billion-year lifetimes of stars. Despite their name, they have nothing to do with planets; the term originated because of their planet-like appearance in early telescopes.

WikidataRate this definition:0.0 / 0 votes

1. Planetary nebula

   A planetary nebula, more correctly known as a stellar-remnant nebula, is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life. The term for this class of objects is a misnomer that originated in the 1780s with astronomer William Herschel, because when viewed through his telescope, these objects were somewhat similar in appearance to Uranus, the planet which he had recently discovered. Herschel's name for these objects was adopted by astronomers and has not been changed, even though planetary nebulae are unrelated to the planets of the solar system. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years. The mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds. Without these opaque layers, the hot, luminous core emits ultraviolet radiation that ionizes the ejected outer layers of the star. This energized shell radiates as a planetary nebula.

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How to pronounce planetary nebula?

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Numerology

1. Chaldean Numerology

   The numerical value of planetary nebula in Chaldean Numerology is: 7

2. Pythagorean Numerology

   The numerical value of planetary nebula in Pythagorean Numerology is: 5

References

1. ^ Princeton's WordNet
   http://wordnetweb.princeton.edu/perl/webwn?s=planetary nebula
2. ^ Wiktionary
   https://en.wiktionary.org/wiki/Planetary_Nebula
3. ^ Wikipedia
   https://en.wikipedia.org/wiki/Planetary_Nebula
4. ^ ChatGPT
   https://chat.openai.com
5. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=planetary nebula