Physical properties of dust particles in cometary comae: from clues to evidence with the Rosetta mission

Abstract : Physical properties of dust in cometary comae have first been approached through unique flyby missions and numerous remote observations of the intensity and polarization of the solar light they scatter. Clues to size distribution, morphology, refractive index of dust particles, and to their variations within comae have been derived from polarimetric data. The Rosetta rendezvous mission to 67P/Churyumov- Gerasimenko (hereafter 67P) is now confirming previous estimations and providing detailed evidence about the dust physical properties, through sophisticated measurements obtained in different regions of the coma and for different solar distances.