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K.J. Kossacki (MPI), K.J. Kossacki (UW), S. Szutowicz (CBK), J. Leliwa-Kopystynski (UW), J. Leliwa-Kopystynski (CBK)
The cometary nuclei are composed mostly of water ice and mineral grains. Volatiles sublimate however when a comet passes near the Sun, leading to the formation of a dust layer covering the nucleus. Various other metamorphic processes are also predicted to modify the subsurface layer of the nucleus. Consequently, it should become stratified and more cohesive than initially. At present, due to the preparation of the mission Rosetta to the comet 46P/Wirtanen it is especially important to understand the processes responsible for the evolution of a cometary nucleus. This can be of key importance for the successful landing on the nucleus and further interpretation of the results of the mission.
This work is mostly intended to estimate how quickly the process of grain sintering could modify the outer part of nucleus. The other effects, like crystallization of water ice are however also taken into account. The simulation is performed for the time period from 1948 to 2016. The orbit of the comet is calculated according to the forced precession model. The evolution of the material texture and temperature distribution below the dust layer is simulated according to the selfconsistent model of the thermal and structural evolution of an initially homogeneous ice--dust mixture. The present analysis includes the presence of amorphous water ice and other, non-water volatiles. They are assumed initially trapped in amorphous water ice.
It is found, that the cohesive layer from about one meter up to about ten meters thick can be formed, depending on the size of ice grains and the properties of the dust mantle.
The author(s) of this abstract have provided an email address for comments about the abstract: kjkossac@osf2.mpae.gwdg.de