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Paper: On the Fly Imaging of Neutral and Ionized Molecules in Comet Hale-Bopp
Volume: 217, Imaging at Radio Through Submillimeter Wavelengths
Page: 82
Authors: Womack, M.; Pinnick, D. A.; Magnum, J. G.; Festou, M. C.; Stern, S. A.
Abstract: On-the-Fly maps of emission were obtained for CO, HCN, H2 CO and HCO+ at 226 - 267 GHz for Comet Hale-Bopp during perihelion using the NRAO 12-m telescope. These are the first successful OTF maps obtained of a comet with the NRAO 12-m telescope. The maps cover an angular extent of ~ 3 - 6 arcminutes with sample sizes of ~ 6 - 8 arcseconds, depending on the frequency observed. The HCN emission appears symmetric about the center of brightness, while CO emission is elongated along the sun-comet-tail direction. The HCO+ emission is more diffuse than the neutral molecules and its maximal brightness appears significantly offset from the nucleus along the tailward direction. The HCO+ intensity is also significantly decreased near the nuclear region. In order to minimize observing artifacts, we scanned alternately in RA and Dec, and checked the pointing and focus were checked after each map. The data were reduced using the AIPS package and are being analyzed with the IDL and IRAF packages. In addition to emission morphology and spatial profiles, we will measure changes in spectral emission linewidth and lineshift as a function of position in the coma. The data present an excellent opportunity to probe the physical and chemical behavior of neutral and charged species in the cometary atmosphere.
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