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Far Ultraviolet Excitation Processes in Comets

Published online by Cambridge University Press:  12 April 2016

P. D. Feldman ,
C. B. Opal ,
R. R. Meier  and
K. R. Nicolas

Extract

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The recent observations of atomic oxygen and carbon in the far ultraviolet spectrum of Comet Kohoutek (1973f) (Feldman et al. 1974; Opal et al. 1974) have demonstrated the existence of these atomic species in the cometary coma. However, in order to identify the source of their origin, it is necessary to relate the observed ultraviolet flux to the atomic production rate. Assuming the only excitation mechanisms allowed are those produced by resonance scattering and fluorescence of solar ultraviolet radiation, the problem reduces to finding the emission rate factors (g-factors) as a function of the heliocentric comet velocity. Since the widths of the solar emission lines are smaller than the maximum heliocentric Doppler shift, given by

where q is the perihelion distance in A.U., it is necessary to consider the detailed multiplet structure of the transition, the solar line shape and the relaxation of excited fine structure levels.

Type
Part II
Information
International Astronomical Union Colloquium , Volume 25 , Issue Part2: The Study of Comets , 1976 , pp. 773 - 796
Copyright
Copyright © NASA 1976

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