Decimeter-scale particle characterization in the coma of 73P/Schwassmann-Wachmann 3 using dual-wavelength radar observations

We investigate the centimeter-to-decimeter-scale particle size distribution and dynamics in the coma of Comet 73P/Schwassmann-Wachmann 3 using radar observations obtained shortly after the comet's disintegration in May 2006. We derive the particle size distribution power-law index in the comae of fragments B and C using radar cross sections and circular-polarization ratios observed at S and X bands (2.38 GHz and 8.56 GHz, respectively), and show day-to-day changes in the number of contributing particles. We test three irregular particle morphologies, but find that the particle shape plays a relatively minor role. The power-law indices from 4.0 to 4.8 and major-axis diameters up to about 30 cm provide the best fits to the radar observations, the values depending on the particle shape and the observed radial velocity. A majority of the measured particle velocities exceed the escape velocity of the nuclei.