37th DPS Meeting, 4-9 September 2005
Session 11 Comets
Oral, Monday, September 5, 2005, 4:20-6:00pm, Law LG19

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[11.04] The Dust Size Distribution In The Trail Of 67P/Churyumov-Gerasimenko From Observation And Modelling

J. Agarwal (MPIK, Heidelberg), H. Boehnhardt (MPS, Katlenburg-Lindau), M. Mueller (EDS at ESA/ESOC, Darmstadt), E. T. Gruen (MPIK, Heidelberg & HIGP, Hawaii)

We have taken optical images of the dust trail and neckline of comet 67P/Churyumov-Gerasimenko in April 2004 with the Wide Field Imager at MPG/ESO 2.2m telescope (La Silla). Based on these images we constrain the size distribution of mm-sized dust particles ejected from the comet. Such particles concentrate close to the comet's orbit due to weak radiation pressure and low emission speeds, thereby forming the comet's dust trail. They represent a significant fraction of the total mass contributed by comets to the interplanetary dust environment. By fitting simulated images to the measured intensities we evaluate the size distribution of the trail particles. The model parameters are derived from the observed emission history of Churyumov-Gerasimenko. Preliminary analysis indicates a flatter size distribution than previously assumed. The size distribution is a crucial parameter for estimating the number density of large particles in the vicinity of Churyumov-Gerasimenko and hence for the safety of ESA's Rosetta spacecraft, which will pass through the trail region during its approach to this comet in 2013.

This work is based on observations made with the 2.2m telescope in La Silla (Chile) operated by the European Southern Observatory and the Max Planck Society. Support for it was provided by the German National Academic Foundation.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.