EDP Sciences
Free Access
Volume 397, Number 3, January III 2003
Page(s) 1109 - 1122
Section The Sun
DOI https://doi.org/10.1051/0004-6361:20021550
Published online 21 January 2003

A&A 397, 1109-1122 (2003)
DOI: 10.1051/0004-6361:20021550

Long-term optical spectrophotometric monitoring of comet C/1995 O1 (Hale-Bopp)

H. Rauer1, J. Helbert1, C. Arpigny2, J. Benkhoff1, D. Bockelée-Morvan3, H. Boehnhardt4, F. Colas5, J. Crovisier3, O. Hainaut4, L. Jorda6, M. Kueppers7, J. Manfroid2 and N. Thomas8

1  DLR, Institute of Space Sensor Technology and Planetary Exploration, Rutherfordstr. 2, 12489 Berlin, Germany
2  Institut d'Astrophysique et Géophysique, Sart Tilman B5c, 4000 Liège, Belgium
3  Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon, France
4  European Southern Observatory, Alonso de Cordova 3107, Santiago de Chile
5  Bureau des Longitudes, 77 avenue Denfert Rochereau, 75014 Paris, France
6  Laboratoire d'Astrophysique de Marseille, Site Pereisc, 13376 Marseille Cedex 12, France
7  Physikalisches Institut, Univ. Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
8  MPI für Aeronomie, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany

(Received 24 July 2002 / Accepted 25 October 2002 )

We observed comet C/1995 O1 (Hale-Bopp) at 4.6-2.9 AU pre-perihelion and 2.8-12.8 AU post-perihelion with optical long-slit spectroscopy. Emission bands of CN, C 3, C 2 and NH 2 have been covered. Emission of C 3 was detected up to 7.0 AU, and CN could be followed up to 9.8 AU post-perihelion. Spatial column density profiles of the radicals have been used to derive effective parent Haser scale lengths for heliocentric distances beyond 3 AU. Production rates were derived based on these Haser scale lengths. The observations of CN are in agreement with HCN as the major parent molecule of this radical at large distances from the Sun (i.e. beyond ~3 AU). We compare the measured CN production rate to sublimation rates of HCN from a simple nucleus sublimation model. The variation of CN production rates with changing heliocentric distance gives no indication for sublimation from the interior and is consistent with very little thermal lag of the nucleus.

Key words: comets: general -- comets: individual: C/1995 O1 (Hale-Bopp) -- solar system: general

Offprint request: H. Rauer, heike.rauer@dlr.de

© ESO 2003

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