Abstract 

During the seminar, a new flux-nuclear mechanism was presented, which explains the causes of cometary outbursts. This mechanism should be considered as a two-stage process. In the first stage, it is necessary to take into account the sublimation flux that occurs through the porous structure of the cometary nucleus. The second stage is the reaction of the comet nucleus to the occurring sublimation. The consequence of this process is the migration (redistribution) of porous agglomerates on the surface of the cometary nucleus, the formation of landslides (local avalanches), the formation of dunes, the emission of porous agglomerates to the coma and the loosening of the surface layer, which is consequently destroyed. Let us note that these processes are part of the broadly understood cometary activity, i.e. the interaction of sublimating ice with the comet nucleus. As a result of intensive sublimation of ice, the loosened cometary material is thrown into the coma, which causes an increase in the total scattering cross-section. An additional contribution to this scattering cross-section is the emission of matter particles via jets. In such a case, these particles, with a local narrowing of the jet channel, can lead to its complete or partial blockage. This leads to an increase in the pressure of the gas trapped in the cavity. If the value of the pressure of the trapped gas exceeds the mechanical strength to cracking, then a fragment (upper part) or even the entire cavity is destroyed. The effect of such destruction is the disintegration of this fragment of the nucleus into porous primary agglomerates and their emission to the coma. Then the incident sunlight is effectively scattered, which leads to an increase in the brightness of the comet, i.e. its outburst.

Email registration for the seminar with Dr. hab. Konrad Kossacki, University Professor: Konrad.Kossacki@fuw.edu.pl