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Cometary activity, discrete outgassing areas, and dust-jet formationConceptual models for various types of features observed in cometary comae (jets, spirals, halos, fans, etc.), their computer simulation, and the hydrodynamic models for jet formation are critically reviewed, and evidence for anisotropic, strongly collimated flows of ejecta emanating from discrete active regions (vents) on the rotating cometary nuclei is presented. Techniques employed to generate synthetic comet images that simulate the features observed are described, and their relevance to the primary objects of coma-morphology studies is discussed. Modeling of temporal variations in the water emission from discrete active regions suggests that production curves asymmetric with respect to perihelion should be commonplace. Critical comparisons with the activity profiles of Enke's comet and with light curves of disappearing comets and comets that undergo outbursts are presented. Recent developments in the understanding of the processes that cause the nongravitational perturbations of cometary motions are reviewed, and the observed discontinuities are identified with the birth of new sources and/or deactivation of old vents.
Document ID
19930029584
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Sekanina, Z.
(JPL Pasadena, CA, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1991
Publication Information
Publication: In: Comets in the post-Halley era. Vol. 2 (A93-13551 02-90)
Publisher: Kluwer Academic Publishers
Subject Category
Astrophysics
Accession Number
93A13581
Distribution Limits
Public
Copyright
Other

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