We report imaging polarimetry of segments B and C of the Jupiter-family Comet 73P/Schwassmann-Wachmann 3 in the I and H bandpasses at solar phase angles of approximately 35 and 85 \arcdeg .
The level of polarization was typical for active comets , but larger than expected for a Jupiter-family comet .
The polarimetric color was slightly red ( \frac { \delta P } { \delta \lambda } = +1.2 \pm 0.4 ) at a phase angle of \sim 35 \arcdeg and either neutral or slightly blue at a phase angle of \sim 85 \arcdeg .
Observations during the closest approach from 2006 May 11-13 achieved a resolution of 35 Â km at the nucleus .
Both segments clearly depart from a 1 / \rho surface brightness for the first 50 - 200 Â km from the nucleus .
Simulations of radiation driven dust dynamics can reproduce some of the observed coma morphology , but only with a wide distribution of initial dust velocities ( at least a factor of 10 ) for a given grain radius .
Grain aggregate breakup and fragmentation are able to reproduce the observed profile perpendicular to the Sun-Comet axis , but fit the observations less well along this axis ( into the tail ) .
The required fragmentation is significant , with a reduction in the mean grain aggregate size by about a factor of 10 .
A combination of the two processes could possibly explain the surface brightness profile of the comet .