Detection of large grains in the coma of Comet C/2001 A2 (LINEAR) from Arecibo radar observations

Michael C. Nolan, John K. Harmon, Ellen S. Howell, Donald B. Campbell, Jean-Luc Margot
2006 Icarus (New York, N.Y. 1962)  
Arecibo S-band (lambda=13cm) radar observations of Comet C/2001 A2 (LINEAR) on 2001 July 7-9 showed a strong echo from large coma grains. This echo was significantly depolarized. This is the first firm detection of depolarization in a grain-coma radar echo and indicates that the largest grains are at least lambda / 2 or 2 cm in radius. The grains are moving at tens of m/s with respect to the nucleus. The non-detection of the nucleus places an upper limit of 3 km on its diameter. The broad,
more » ... etric echo power spectrum suggests a fan of grains that have a steep (differential number ~ a^-4) size distribution at cm-scales, though the observed fragmentation of this comet complicates that picture.
doi:10.1016/j.icarus.2005.11.010 fatcat:hiinmeepebdlthyxynvkzfvjxi