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, CH3OH, H2CO, H2S, CS, CH3CN and HNC) were monitored. CS, H2S, H2CO, CH3CN were detected up to rh= 3–4 AU from the Sun, while HCN and CH3OH 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 rh= 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 rh -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 rhare 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 CH3OH and CO lines, increased with decreasing rh, from about 10 K at 7 AU to 110 K around perihelion.
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Biver, N., Bockelée-Morvan, D., Colom, P. et al.: 1997, ‘Evolution of the Outgassing of Comet Hale-Bopp (C/1995 O1) from Radio Observations’, Science 275, 1915–1918.
Biver, N., Bockelée-Morvan, D., Colom, P. et al.: 1999a, ‘Long-Term Evolution of the Outgassing of Comet Hale-Bopp from Radio Observations’, Earth Moon Planets 78, 5–11.
Biver, N., Bockelée-Morvan, D., Crovisier, J. et al.: 1999b, ‘Spectroscopic Monitoring of Comet C/1996 B2 (Hyakutake) with the JCMT and IRAM Radio Telescopes’, Astron. J. 118, 1850–1872.
Biver, N., Bockelée-Morvan, D., Crovisier, J. et al.: 2002, ‘Chemical Composition Diversity among 24 Comets Observed at Radio Wavelengths’, these proceedings.
Biver, N., Rauer, H., Despois, D. et al.: 1996, ‘Substantial Outgassing of CO from Comet Hale-Bopp at Large Heliocentric Distance’, Nature 380, 137–139.
Bockelée-Morvan, D., Crovisier, J., Colom, P., and Despois, D.: 1994, ‘The Rotational Lines of Methanol in Comets Austin 1990 V and Levy 1990 XX’, Astron. Astrophys. 287, 647–665.
Bockelée-Morvan D., Moreno, R., Biver, N. et al.: 1996, ‘Comet C/1995 O1 (Hale-Bopp)’, IAUC 6511.
Capria, M. T., Coradini, A., De Sanctis, M. C., and Orosei, R.: 2000, ‘CO Emission Mechanisms in C/1995 O1 (Hale-Bopp)’, Astron. Astrophys. 357, 359–366.
Colom, P., Crovisier, J., Bockelée-Morvan, D., Despois, D., and Paubert, G.: 1992, ‘Formaldehyde in Comets I. Microwave Observations of P/Brorsen-Metcalf (1989 X), Austin (1990 V) and Levy (1990 XX)’, Astron. Astrophys. 264, 270–281.
Colom, P., Gérard, E., Crovisier, J. et al.: 1999, ‘Observations of the OH radical in Comet Hale-Bopp with the Nançay Radio Telescope’, Earth Moon Planets 78, 37–43.
Cottin, H., Gazeau, M. C., Benilan, Y., and Raulin, F.: 2001, ‘Polyoxymethylene as Parent Molecule for the Formaldehyde Extended Source in Comet Halley’, Astrophys. J. 556, 417–420.
Crifo, J.-F., Rodionov, A. V., and Bockelée-Morvan, D.: 1999, ‘The Dependence of the Circumnuclear Coma Structure on the Properties of the Nucleus. III. First Modeling of a CO-Dominated Coma, with Application to Comets 46P/Wirtanen and 29P/Schwassmann-Wachmann 1’, Icarus 138, 85–106.
Crovisier, J.: 1994, ‘Photodestruction Rates for Cometary Parent Molecules’, J. Geophys. Res. 99-E2, 3777–3781.
Crovisier, J., Biver, N., Bockelée-Morvan, D. et al.: 1995, ‘Carbon Monoxide Outgassing from Comet P/Schwassmann-Wachmann 1’, Icarus 115, 213–216.
Crovisier, J., Leech, K., Bockelée-Morvan, D. et al.: 1999, ‘The Spectrum of Comet Hale-Bopp as seen by ISO’, ESA-SP 427, 137–140.
Enzian, A., Cabot, H., and Klinger, J.: 1998, ‘Simulation of the Water and Carbon Monoxide Production Rates of Comet Hale-Bopp Using a Quasi 3D Nucleus Model’, Planet. Space Sci. 46, 851–858.
Gunnarsson, M., Rickman, H., Festou, M. C., Winnberg, A., and Tancredi, G.: 2002, ‘An Extended CO Source around Comet 29P/Schwassmann-Wachmann 1’, Icarus, in press.
Irvine, W. M., Schloerb, F. P., Dickens, J. E. et al.: 1999, ‘The HNC/HCN Ratio in Comets’, Earth Moon Planets 78, 29–35.
Jewitt, D., Senay M., and Matthews H.: 1996, ‘Observations of Carbon Monoxide in Comet Hale-Bopp’, Science 271, 1110–1113.
Meier, R., Eberhardt, P., Krankowsky, D., and Hodges, R. R.: 1993, ‘The Extended Formaldehyde Source in Comet Halley’, Astron. Astrophys. 277, 677–690.
Rauer, H., Helbert, J., Arpigny, C. et al.: 2002, ‘Long-Term Optical Spectrophotometric Monitoring of Comet C/1995 O1 (Hale-Bopp)’, Astron. Astrophys., in press.
Rodgers, S. D. and Charnley, S. B.: 1998, ‘HNC and HCN in Comets’, Astrophys. J. Lett. 501, L227-L230.
Stern, S. A., Colwell, W. B., Festou, M. C. et al.: 1999, ‘Comet Hale-Bopp (C/1995 O1) near 2.3 AU Post-Perihelion: Southwest Ultraviolet Imaging System Measurements of the H2O and Dust Productions’, Astron. J. 118, 1120–1125.
Weaver, H. A., Feldman, P. D., A'Hearn, M. F., Arpigny, C., Brandt, J. C., and Stern, S. A.: 1999, ‘Post-perihelion HST Observations of Comet Hale-Bopp (C/1995 O1)’, Icarus 141, 1–12.
Wink J., Bockelée-Morvan D., Despois, D. et al.: 1999, ‘Evidences for Extended Sources and Temporal Modulations in Molecular Observations of C/1995 O1 (Hale-Bopp) at IRAM Interferometer’, Earth Moon Planets 78, 63.
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Biver, N., Bockelée-Morvan, D., Colom, P. et al. The 1995–2002 Long-Term Monitoring of Comet C/1995 O1 (HALE–BOPP) at Radio Wavelength. Earth Moon Planet 90, 5–14 (2002). https://doi.org/10.1023/A:1021599915018
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DOI: https://doi.org/10.1023/A:1021599915018