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M. Womack (St. Cloud State University), M.C. Festou (Toulouse Observatory, France), D. Pinnick (St. Cloud State University), J.G. Mangum (NRAO, Tucson, Arizona)
Molecular production rates can be roughly estimated from observations and an isotropic nuclear expansion model with photodissociative decay. However, this is not ideal, because it does not include outgassing from active regions (often resulting in "jets" in images), which are likely to occur for several species in comets. In order to determine the spatial distribution of the gas species around the nucleus and, in particular, investigate the importance of extended sources, we obtained four-dimensional On-the-fly (OTF) datacubes of emission from HCN, CO and H2CO emission in comet Hale-Bopp during perihelion. The OTF data contain spatial information about the emission intensity (first axis) across the angular extent in right ascension and declination (second and third axes) for each frequency channel observed (fourth axis). As a result, both spectra and images can be examined over > 200,000 km across the coma. These data were analyzed in order to determine: 1) what species form jet structures, 2) whether all jet structures are identical, 3) what are the relative weights of the asymmetric and jet-like components, and 4) whether temporal changes are observed, particularly with regard to the nucleus rotation.
MW received support from NSF CAREER and RUI Programs and NASA Planetary Atmospheres.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.