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Astron. Astrophys. 334, L53-L56 (1998)

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Letter to the Editor

Production and kinematics of sodium atoms in the coma of comet Hale-Bopp *

C. Arpigny 1, H. Rauer 2, J. Manfroid 1, D. Hutsemékers 1, E. Jehin 1, J. Crovisier 3 and L. Jorda 4

1 Institut d'Astrophysique et de Géophysique, Avenue de Cointe 5, B-4000 Liège, Belgium
2 DLR, Institut für Planetenerkundung, Rudower Chaussee 5, D-12484 Berlin, Germany
3 Observatoire de Paris-Meudon, 5 Place Jules Janssen, F-92190 Meudon, France
4 MPI für Aeronomie, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau, Germany

Received 13 November 1997 / Accepted 9 April 1998


High-resolution spectra of sodium D line emission in comet Hale-Bopp (C/1995 O1) were obtained at the Observatoire de Haute-Provence, France, on 25-27 March and on 15-17 April, 1997. The observations have been used to measure the velocity of sodium atoms in the coma within 2 105 km from the nucleus. A comparison between the March and April data provides an illustration of the influence of the heliocentric radial velocity on the strength of the fluorescence (Swings effect), and on the velocity of Na atoms achieved by solar radiation pressure acceleration. Evidence for the presence of a distributed source in the coma is found from the relatively high tailward velocities on the sunward side of the coma, in addition to the sunward extent of sodium emission up to 1.4 105 km in April.

Key words: comets: general – Comet: C/1995 O1 (Hale-Bopp) – atomic processes – line: profiles

* Based on observations secured at OHP (France)


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© European Southern Observatory (ESO) 1998

Online publication: May 15, 1998