Scattering and Emission of Light by Comet Dust

• Applicant: Dr. Johannes Markkanen
• Subject Area: Astrophysics and Astronomy
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517146316

We propose to develop a self-consistent physics-based numerical model for light scattering and thermal emission by dust particles in order to understand activity of comets. Modeling light scattering and thermal emission by realistic cosmic dust and ice particles constitutes an open computational problem. We will develop a fast full-wave numerical solution based on the integral equations for small particles, and approximate dense medium radiative transfer methods for large particles. The methods will be incorporated into a thermophysical model to account for the effects of heat and gas transfer and sublimation of ices. We will constrain physical properties of dust and ice particles by comparing the simulation results to the multi-instrument ground- and space-based observational data covering the visual and thermal infrared part of the spectrum. Compared to models addressing only one of these spectral regions, we expect to obtain much stronger constraints on the particle properties by simultaneously modelling the visual and thermal part using the self-consistent model. With the help of dynamical simulations we will investigate the effects of dynamical sorting, sublimation, fragmentation and alignment of particles in the cometary comae. The results of this research will have a major impact on the scientific communities in the field of planetary science through publicly available high-performance computational tools for the synoptic analysis of scattering, emission, and dust’s energy budget. The project opens new roads for analyzing multi-instrument and multi-physics data self-consistently. The project improves our understanding of active solar system bodies. In particular, we study the processes that reshape the properties of dust and ice particles after being lifted off the comet's surface, and their temporal evolution with respect to the heliocentric distance. This helps us to evaluate the near surface dust environment, surface properties and mechanisms driving the activity from the ground-based observations. In general, such knowledge finds applicatations in constraining the solar system's formation models and in planning future space missions to the active solar system bodies such as ESA's Comet Interceptor.

• DFG Programme: Research Grants