Light scattering by icy cometary dust particles

Long-period comets exhibit dust activity well beyond the water‐ice snow line, which implies that dust release from the nucleus cannot be driven by water‐ice sublimation (Meech & Svoren, 2004. Comets II, 2004) This further suggests that large particles in the coma remain relatively unprocessed and may preserve a dust‐to‐water‐ice ratio similar to that of the nucleus—a key, yet still unknown, parameter that influences thermophysics of comets. 

In this study, we carry out numerical simulations of light scattering by both icy and ice‐free cometary particles using state-of-the-art solvers (Markkanen & Yuffa, JQSRT 189, 2017, Muinonen et al. Opt. Lett 43, 2018). We then compare observables—such as the degree of linear polarization and spectral color—to assess their sensitivity to ice content and to infer the internal mixing of ice and dust within individual particles. Finally, these models are applied to distant comets (e.g. Ivanova et al. in the present meeting)

Acknowledgements: JM was supported by Deutche Forschungsgemeinschaft (DFG) no 517146316. The authors acknowlwedge support from Deutscher Akademischer Austausschdienst and Slovak Academy of Sciences (DAAD-SAV) project 57752921.