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Proceedings Paper

Episodic aging and end states of comets
Author(s): Zdenek Sekanina
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Paper Abstract

It is known that comets are aging very rapidly on cosmic scales, because they rapidly shedmass. The processes involved are (i) normal activity-sublimation of ices and expulsion of dust from discrete emission sources on and/or below the surface of a comet's nucleus, and (ii) nuclear fragmentation. Both modes are episodic in nature, the latter includes major steps in the comet's life cycle. The role and history of dynamical techniques used are described and results on mass losses due to sublimation and dust expulsion are reviewed. Studies of split comets, Holmes-like exploding comets, and cataclysmically fragmenting comets show that masses of 10 to 100 million tons are involved in the fragmentation process. This and other information is used to investigate the nature of comets' episodic aging. Based on recent advances in understanding the surface morphology of cometary nuclei by close-up imaging, a possible mechanism for large-scale fragmentation events is proposed and shown to be consistent with evidence available from observations. Strongly flattened, pancake-like shapes appear to be required for comet fragments by conceptual constraints. Possible end states are briefly examined.

Paper Details

Date Published: 28 August 2008
PDF: 15 pages
Proc. SPIE 7097, Instruments, Methods, and Missions for Astrobiology XI, 70970X (28 August 2008); doi: 10.1117/12.801143
Show Author Affiliations
Zdenek Sekanina, Jet Propulsion Lab. (United States)


Published in SPIE Proceedings Vol. 7097:
Instruments, Methods, and Missions for Astrobiology XI
Richard B. Hoover; Gilbert Victor Levin; Alexei Yu. Rozanov; Paul C.W. Davies, Editor(s)

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