Interaction of Electromagnetic Radiation with Cometary Dust

The chapter overviews the recent developments in the remote sensing of cometary dust using visible, near-infrared, and thermal-infrared radiation, as well as interaction of the dust with electromagnetic radiation, which affects the dynamics of dust particles. It considers photometric, polarimetric, and spectral studies of cometary dust, focusing on those observables and correlations between them that allow revealing the composition, size, and structure of the dust particles. The analysis includes the observed brightness and polarization phase curves, color and polarimetric color of the cometary dust, and near- and thermal-infrared spectra. Special attention is paid to the role of gas contamination in the polarimetric and photometric data. A review of modeling efforts to interpret the observational results is also provided, describing the most popular (and some novel) techniques used in the computer modeling of light scattering by dust particles with a focus on modeling the most complex type of cometary particles: fluffy and porous agglomerates. The chapter also considers how properties of the dust particles affect their photoelectric emission and their response to the radiation pressure and radiative torque, including alignment and fragmentation of particles. Results of computer and some laboratory modeling are analyzed for their consistency with the observational and in situ data. Also discussed is how the modeling results can be combined with in situ data for better characterization of the cometary dust.