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The nature of the solar wind interaction with CO2/CO-dominated cometsThe nature of the interaction of the solar wind with the ionospheres (field-free ion cavities) of comets with CO or CO2 as their dominant volatile species is considered and compared with the solar wind interaction with H2O-diominated comets. Calculations of the heliocentric variation of scale lengths defined as the nuclear distance at which the mean free path for ion-neutral collisions becomes equal to the nuclear distance, and the ion and neutral stand-off distances are presented for different modes of energy addition, nuclear radii and ionization time scales. Results indicate that whereas little activity can be expected from H2O-dominated comets at distances beyond 3 AU, COand CO2-dominated comets can be expected to be quite prolific at such distances. In contrast to H2O-dominated comets characterized by weak shocks, CO/CO2-dominated comet solar wind interactions are found to produce strong bow shocks within a specific heliocentric distance for the isothermal case of a CO-dominated comet, and a weak shock outside of this distance. In the general case, two types of cometary ionosphere transitions are found: a transition from strong to weak bow shock and from a compressible (soft) to an incompressible (hard) ionosphere, and a transition from a soft to a hard ionosphere with the bow shock remaining weak at a heliocentric distance dependant on atmospheric optical depth, bolometric albedo, nuclear radius, latent heat of sublimation of nuclear material, ionization time scale and type of heat addition. It is pointed out that the behavior of Comet Humason can be explained by solar wind interactions with a CO- or CO2-dominated comet.
Document ID
19810056900
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Houpis, H. L. F.
(California Univ. La Jolla, CA, United States)
Mendis, D. A.
(California, University La Jolla, CA, United States)
Date Acquired
August 11, 2013
Publication Date
August 1, 1981
Publication Information
Publication: Moon and the Planets
Volume: 25
Subject Category
Astrophysics
Accession Number
81A41304
Funding Number(s)
CONTRACT_GRANT: NGR-05-009-110
CONTRACT_GRANT: NSG-7102
CONTRACT_GRANT: NSF AST-78-19008
Distribution Limits
Public
Copyright
Other

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