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[12.09] A Comparison of the Volatile Carbon-Oxygen Chemistry in Several Oort Cloud Comets

M. A. DiSanti, N. Dello Russo (CUA / NASA-GSFC), K. Magee-Sauer (Rowan U.), E. L. Gibb (NAS-NRC / NASA-GSFC), D. C. Reuter (NASA-GSFC), L.-H. Xu (U. New Brunswick), M. J. Mumma (NASA-GSFC)

Since 1996, we have conducted detailed studies of the abundances of parent volatiles in 8 Oort Cloud comets using modern long-slit echelle spectrometers having sensitivity in the 1 – 5 \mu m spectral region. These instruments (CSHELL at the NASA-IRTF, and NIRSPEC at Keck 2) have sufficiently high spectral resolution ( \nu / \Delta \nu ~2 x 10⁴ ) to resolve individual cometary emission lines. Their small pixel sizes provide the high angular resolution necessary for detailed study of the spatial distribution of emissions in the coma.

Here we inter-compare our results for the chemically-linked molecules carbon monoxide (CO), formaldehyde (H₂CO), and methyl alcohol (CH₃OH) among our sample of comets. Such a study can provide clues as to the processing history of the ice. Measuring the relative abundances of these molecules can provide a test of the efficiency of conversion of CO, for example through hydrogen addition on icy grain mantles or by radiation processing in the dense cloud core. Comparisons with fluorescence models and/or laboratory measurements will also be presented where appropriate.

This work is supported by NASA Planetary Astronomy Program grants NAG5-7905 and NAG5-12208 to M. A. DiSanti, and RTOP 693-344-32-30-07 to M. J. Mumma.

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.