Long-term Evolution of the Outgassing of Comet Hale-Bopp From Radio Observations |
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| Authors: | Biver N Bockelée-Morvan D Colom P Crovisier J Germain B Lellouch E Davies J K Dent W R F Moreno R Paubert G Wink J Despois D Lis D C Mehringer D Benford D Gardner M Phillips T G Gunnarsson M Rickman H Winnberg A Bergman P Johansson L E B Rauer H |
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| Institution: | (1) Observatoire de Paris-Meudon, France;(2) Joint Astronomy Centre, Hawaii, USA;(3) Institut de Radio Astronomie Millimétrique, Granada, Spain;(4) Institut de Radio Astronomie Millimétrique, Grenoble, France;(5) Observatoire de Bordeaux, France;(6) Caltech, California, USA;(7) Uppsala Astronomiska Observatorium, Sweden;(8) Onsala Space Observatory, Sweden;(9) Institut für Planetenerkundung, DLR, Berlin, Germany |
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| 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.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | Comets C/1995 O1 (Hale-Bopp) radio observations molecules |
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