Abstract
C/1995 O1 (Hale-Bopp) has been observed on a regular basis since August 1995 at millimetre and submillimetre wavelengths using IRAM, JCMT, CSO and SEST radio telescopes. The production rates of eight molecular species (CO, HCN, CH3OH, H2CO,H2S, CS, CH3CN,HNC) have been monitored as a function of heliocentric distance(rh from 7 AU pre-perihelion to 4 AU post-perihelion. As comet Hale-Bopp approached and receded from the Sun, these species displayed different behaviours. Far from the Sun, the most volatile species were found in general relatively more abundant in the coma. In comparison to other species, HNC, H2CO and CS showed a much steeper increase of the production rate with decreasing rh. Less than 1.5 AU from the Sun, the relative abundances were fairly stable and approached those found in other comets near 1 AU.
The kinetic temperature of the coma, estimated from the relative intensities of the CH3OH and CO lines, increased with decreasing rh, from about10 K at 7 AU to 110 K around perihelion. The expansion velocity of the gaseous species, derived from the line shapes, also increased with a law close torh 3.
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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.
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.
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)’, IAU Circular No. 6511.
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.: 1997, ‘Observations of the OH Radical in Comet C/1995 O1 (Hale-Bopp) with the Nançay Radio Telescope’, Earth, Moon, and Planets 78, 37–43.
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.
Enzian, A., Cabot, H., and Klinger, J.: 1998, ‘Simulation of the Water and Carbon Monoxide Production Rates of Comet Hale-Bopp Using a Quasi 3-D Nucleus Model’, Planet. Space Sci. 46, 851–858.
Irvine, W. M., Dickens, J. E., Lovell, A. J. et al.: 1997, ‘The HNC/HCN Ratio in Comets’, Earth, Moon, and 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.
Rodgers, S. D. and Charnley, S. B.: 1998, ‘HNC and HCN in Comets’, Astrophys. J. Lett. 501, L227–L230.
Wink, J., Bockelée-Morvan D., Despois, D. et al.: 1997, ‘Evidences for Extended Sources and Temporal Modulations in Molecular Observations of C/1995 O1 (Hale-Bopp) at the IRAM Interferometer’, Earth, Moon, and Planets 78, 63.
Womack, M., Festou, M. C., and Stern, S. A.: 1997, ‘The Heliocentric Evolution of Key Species in the Distantly-Active Comet C/1995 O1 (Hale-Bopp)’, Astron. J. 114, 2789–2795.
Woodney, L. M., A'Hearn, M. F., McMullin, J., and Samarasinha, N.: 1997, ‘Sulfur Chemistry at Millimeter Wavelengths in C/Hale-Bopp’, Earth, Moon, and Planets 78, 69–70.
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Biver, N., Bockelée-Morvan, D., Colom, P. et al. Long-term Evolution of the Outgassing of Comet Hale-Bopp From Radio Observations. Earth, Moon, and Planets 78, 5–11 (1997). https://doi.org/10.1023/A:1006229818484
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DOI: https://doi.org/10.1023/A:1006229818484