Extinct comet
'Extinct comets are those that have expelled most of their volatile ice and have little left to form a tail or coma. In other words, over time most of the volatile material contained in a comet nucleus evaporates away, and the comet becomes a small, dark, inert lump of rock or rubble[1] that can resemble an asteroid.
When discovered, asteroids were seen as a class of objects distinct from comets, and there was no unified term for the two until "Small Solar System body" was coined in 2006 by the IAU. The main difference between an asteroid and a comet is that a comet shows a coma due to sublimation of near surface ices by solar radiation. A few objects have ended up being dual-listed because they were first classified as minor planets but later showed evidence of cometary activity. Conversely, some (perhaps all) comets are eventually depleted of their surface volatile ices and become asteroids. A further distinction is that comets typically have more eccentric orbits than most asteroids; most "asteroids" with notably eccentric orbits are probably dormant or extinct comets. Also, they are theorized to be common objects amongst the celestial bodies orbiting close to the Sun. [2]
Roughly six percent of the near-earth asteroids are thought to be extinct nuclei of comets which no longer experience outgassing.[3] ref name = "MorbidelliAstIII">A. Morbidelli, W. F. Bottke Jr., Ch. Froeschlé, P. Michel (2002). W. F. Bottke Jr., A. Cellino, P. Paolicchi, and R. P. Binzel (ed.). "Origin and Evolution of Near-Earth Objects" (PDF). Asteroids III. University of Arizona Press: 409–422. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)</ref> [4].
Other related types include "transition comets", that close to becoming extinct, such looked for in the Hubble search for transition comets. Another possibility is volitiels
Extinct comets=
Suspected or theorized extinct comets.
References
- ^ "If comets melt, why do they seem to last for long periods of time?", Scientific American, November 16, 1998
- ^ "SOHO's new catch: its first officially periodic comet". European Space Agency. 25 September 2007. Retrieved 2007-11-19.
- ^ Whitman, Kathryn (2006). "The Size-Frequency Distribution of Dormant Jupiter Family Comets". Retrieved 2008-02-06.
{{cite journal}}: Cite journal requires|journal=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ D.F. Lupishko, M. di Martino and T.A. Lupishko (2000). "What the physical properties of near-Earth asteroids tell us about sources of their origin?". Kinematika i Fizika Nebesnykh Tel Supplimen (3): 213–216.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ D.F. Lupishko, M. di Martino and T.A. Lupishko (2000). "What the physical properties of near-Earth asteroids tell us about sources of their origin?". Kinematika i Fizika Nebesnykh Tel Supplimen (3): 213–216.
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