Aims. The purpose of this study is to test our numerical model of cometary dust coma structures and to use the results to infer information about the nucleus surface activity of comet 9P/Tempel 1. Methods. Parameters on the activity were first estimated from simulations of ground-based observation acquired during the pre-perihelion period (January to June 2005) and compared with published results for the same period. The parameters retrieved were then used to simulate previously unpublished images of the comet acquired during the post-perihelion period (in July and August 2005). Results. Our model was able to retrieve the spin axis orientation of comet 9P/Tempel 1 as well as information on active regions at the surface of the nucleus. We could localize at least six active areas and characterize them with parameters such as the velocity of the dust particles, grain size, and activity profile. Our model confirms published results from spacecraft measurements but is also able to make realistic predictions on the evolution of the coma morphology during the post-perihelion period. © ESO, 2010.

We would like to thank Peter Thomas and collaborators for providing us the shape model of 9P/Tempel 1. We also wish to thank the observers at the Calar Alto and La Silla observatories who have performed the service mode observations used in our analysis. Without their dedication and care the images would not be available. It should be noted that the determination of the orientation of the rotation axis of 9P/Tempel 1 using ground-based observations has benefit from the relatively long time interval and from the regular sampling of the telescope imaging the comet. In particular, this time period had covered a significant part of the perihelion arc of the orbit, when the activity is the highest and the changes in viewing geometry of the comet are the largest. L. M. Lara acknowledges the Ministry of Science and Innovation in Spain for having funded this work through project ESP2006-02934.