| Abstract: Comets are one of the most pristine bodies in the Solar System, preserving material from its earliest stage of formation. Cometary nuclei is the source of molecules and dust particles that form the majority of cometary atmosphere which is observed through ground and space based observations. Understanding the physical processes inside and at the surface of cometary nuclei is therefore essential for linking observational signatures to the underlying structure, compositions and processes.
Recent spacecraft missions have provided data on cometary nuclei, in particular high resolution three dimensional shape models. Employing these models is essential for examining how local topography, solar insolation, and heterogeneous material distributions affect cometary activity.
In this work, I present a thermo-physical model that based directly on these 3D nucleus shapes, the framework combines three models that together simulate the key physical processes controlling cometary evolution. First, the sublimation model captures surface processes including incident solar insolation, thermal reradiation, heat conduction and volatile sublimation. Second, the thermal model describes subsurface heat conduction by solving the one dimensional heat diffusion equation with depth and time dependent material properties of the nucleus. Last, the gas diffusion model links the evolving thermal structure with volatile transport. By accounting for the dynamic distribution of volatiles and dust, the model solves one dimensional pressure diffusion equation to compute sublimation fluxes from individual facets.
By applying this framework to realistic 3D shape models, we investigate how surface morphology and heterogeneous composition govern localized sublimation, dust mantling, and pressure-driven gas flow. The approach enables tracking of spatial and temporal variations in temperature, gas fluxes and compositional changes across the nucleus. Ultimately, the model serves to connect in situ spacecraft measurements with remote observations of cometary comae, and the fundamental physical processes active within comet nuclei.
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