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Ion abundances and implications for photochemistry in comets Halley (1986 III) and Bradfield (1987 XXIX).

Lutz, Barry L. and Womack, Maria and Wagner, R. Mark. (1993) Ion abundances and implications for photochemistry in comets Halley (1986 III) and Bradfield (1987 XXIX). Astrophysical Journal, 407 (Copyri). pp. 402-11. ISSN 1538-4357


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Publisher’s or external URL: http://dx.doi.org/10.1086/172523


Spectra of the plasma tails of comets P/Halley (1986 III) and P/Bradfield (1987 XXIX, also 1987s) were recorded using the Ohio State University Image Dissector Scanner (IDS) on the Perkins 1.8 m telescope at the Lowell Observatory. The ionic species CO+, N2+, CH+, and H2O+ were identified in these spectra and column densities for them were calcd. from measured fluxes. The obsd. abundance ratios of CO+/H2O+ in comets Halley and Bradfield are consistent with predictions by photochem. models, provided that CO+ and H2O+ are produced primarily from photoionization of CO and H2O, resp. However, the obsd. N2+/H2O+ ratios are at least an order of magnitude lower and the obsd. CH+/H2O+ ratios are a factor of 100 higher, than theor. results. The abundance ratio N2/CO was derived in the plasma tail of Bradfield from N2+ and CO+ data, and found to be an order of magnitude higher than a value measured in Halley. The relative ion abundances of CH+, N2+, and H2O+ in Halley are consistent with in situ measurements obtained from the Giotto spacecraft. Fluorescence efficiencies have been recalcd. for optical transitions of N2+, CH+, NH, CH, OH+, and CO and are also presented. [on SciFinder(R)]

Item Type: Article
Publisher’s Statement: © 1993 The American Astronomical Society. Provided by the NASA Astrophysics Data System.
ID number or DOI: 10.1086/172523
Keywords: CHEMISTRY; coma; comets, individual (halley, bradfield); dependence; DYNAMICS; franck-condon factors; lifetimes; model; molecular processes; oscillator-strengths; p/halley; System
Subjects: Q Science > QB Astronomy
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 30 Sep 2015 17:35
URI: http://openknowledge.nau.edu/id/eprint/407

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