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Chemico-Physical Models of Cometary Atmospheres

Published online by Cambridge University Press:  04 August 2017

W. F. Huebner ,
J. J. Keady ,
D. C. Boice ,
H. U. Schmidt  and
R. Wegmann
W. F. Huebner
Affiliation:
T-4 Los Alamos National Laboratory, Los Alamos, NM 87545 USA
J. J. Keady
Affiliation:
T-4 Los Alamos National Laboratory, Los Alamos, NM 87545 USA
D. C. Boice
Affiliation:
T-4 Los Alamos National Laboratory, Los Alamos, NM 87545 USA
H. U. Schmidt
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1 D-8046 Garching Fed. Rep. Germany
R. Wegmann
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1 D-8046 Garching Fed. Rep. Germany

Abstract

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Sublimation (vaporization) of the icy component of a cometary nucleus determines the initial composition of the coma gas as it streams outward and escapes. Photolytic reactions in the inner coma, escape of fast, light species such as atomic and molecular hydrogen, and solar wind interaction in the outer coma alter the chemical composition and the physical nature of the coma gas. Models that describe these interactions must include (1) chemical kinetics, (2) coma energy balance, (3) multifluid flow for the rapidly escaping light components, the heavier bulk fluid, and the plasma with separate temperatures for electrons and the remainder of the gas, (4) transition from a collision dominated inner region to free molecular flow of neutrals in the outer region, (5) pickup of cometary ions by the solar wind, (6) counter and cross streaming of neutrals with respect to the plasma which outside of the contact surface also contains solar wind ions, and (7) magnetic fields carried by the solar wind. Progress on such models is described and results including velocity, temperature, and number density profiles for important chemical species are presented and compared with observations.

Type
Comets
Information
Symposium - International Astronomical Union , Volume 120: Astrochemistry , 1987 , pp. 431 - 441
Copyright
Copyright © Reidel 1987 

References

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