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The 1995–2002 Long-Term Monitoring of Comet C/1995 O1 (Hale-Bopp) at Radio Wavelength

Biver, Nicolas and Bockelée-Morvan, Dominique and Colom, Pierre and Crovisier, Jacques and Henry, Florence and Lellouch, Emmanuel and Winnberg, Anders and Johansson, Lars E. B. and Gunnarsson, Marcus and Rickman, Hans and Rantakyrö, Fredrik and Davies, John K. and Dent, William R. F. and Paubert, Gabriel and Moreno, Raphaël and Wink, Jörn and Despois, Didier and Benford, Dominic J. and Gardner, Matt and Lis, Dariusz C. and Mehringer, David and Phillips, Thomas G. and Rauer, Heike (2002) The 1995–2002 Long-Term Monitoring of Comet C/1995 O1 (Hale-Bopp) at Radio Wavelength. In: Cometary Science after Hale-Bopp. IAU Symposium Proceedings Series. Vol.2. No.186. Springer Netherlands , Dordrecht, pp. 5-14. ISBN 9789048161560. https://resolver.caltech.edu/CaltechAUTHORS:20190823-105107263

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Abstract

The bright comet Hale-Bopp provided the first opportunity to follow the outgassing rates of a number of molecular species over a large range of heliocentric distances. We present the results of our observing campaign at radio wavelengths which began in August 1995 and ended in January 2002. The observations were carried out with the telescopes of Nançay, IRAM, JCMT, CSO and, since September 1997, SEST. The lines of nine molecules (OH, CO, HCN, CH_3OH, H_2CO, H_2S, CS, CH_3CN and HNC) were monitored. CS, H_2S, H_2CO, CH_3CN were detected up to r_h = 3–4 AU from the Sun, while HCN and CH_3OH were detected up to 6 AU. CO, which is the main driver of cometary activity at heliocentric distances larger than 3–4 AU, was last detected in August 2001, at r_h = 14 AU. The gas production rates obtained from this programme contain important information on the nature of cometary ices, their thermal properties and sublimation mechanisms. Line shapes allow to measure gas expansion velocities, which, at large heliocentric distances, might be directly connected to the temperature of the nucleus surface. Inferred expansion velocity of the gas varied as r_h^(−0.4) within 7 AU from the Sun, but remained close to 0.4 km s^(−1) further away. The CO spectra obtained at large r h are strongly blueshifted and indicative of an important day-to-night asymmetry in outgassing and expansion velocity. The kinetic temperature of the coma, estimated from the relative intensities of the CH_3OH and CO lines, increased with decreasing r_h, from about 10 K at 7 AU to 110 K around perihelion.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
https://doi.org/10.1007/978-94-017-1088-6_1DOIArticle
ORCID:
AuthorORCID
Benford, Dominic J.0000-0002-9884-4206
Lis, Dariusz C.0000-0002-0500-4700
Additional Information:© Springer Science+Business Media Dordrecht 2002. (Received 26 March 2002; Accepted 12 June 2002) We are grateful to the IRAM, JCMT, CSO and SEST staff for scheduling and assistance during the observations of these long-term projects. SEST is operated jointly by the Swedish National Facility for Radio Astronomy, and by the European Southern Observatory. IRAM is an international institute cofunded by the CNRS, the Max-Planck-Gesellschaft and the Instituto Geogratico Nacional, Spain. The JCMT is operated on behalf of the Particle Physics and Astronomy Research Council of the United Kingdom, the Netherlands Organization for Scientific Research, and the National Research Council of Canada. The CSO is supported by National Science Foundation grant AST 99-80846. The Nançay Radio Observatory is operated by the Unité Scientifique de Nançay of the Observatoire de Paris, associated with the CNRS, and also gratefully acknowledges the financial support of the ConseiI Régional of the Région Centre in France.
Funders:
Funding AgencyGrant Number
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Max-Planck-GesellschaftUNSPECIFIED
Instituto Geogràfico Nacional (IGN)UNSPECIFIED
NSFAST 99-80846
ConseiI Régional of the Région Centre (France)UNSPECIFIED
Subject Keywords:C/1995 O1 (Hale-Bopp); comets; molecules; radio observations
Series Name:IAU Symposium Proceedings Series
Issue or Number:186
Record Number:CaltechAUTHORS:20190823-105107263
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190823-105107263
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98166
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:23 Aug 2019 19:49
Last Modified:03 Oct 2019 21:38

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