Experimentelle und Analytische Planetologie
Cometary and interplanetary dust models
We have obtained a consistent picture of evolution of cosmic dust through a study of interstellar dust,
cometary dust, and interplanetary dust. Dust particles are aggregates consisting of submicron grains that have
a core-mantle structure with a silicate core and a carbonaceous mantle. The core-mantle structure is a result of
condensation of silicates in stellar atmospheres and subsequent accretion of ices on the silicates. The outer ice
layer is transformed into organics by processing in the interstellar medium. The core-mantle grains are
aggregated when they are located in dense interstellar clouds prior to the formation of the solar system. This is
contrary to classical models of interstellar dust, but consistent not only with recent understandings of particle
coagulation, but also with in situ measurements of interstellar dust. The organic component of presolar
interstellar dust has been partly transformed into more refractory carbonaceous materials during the formation
of comets. Further processing of the organic component is expected in the interplanetary space after the dust
particles are ejected from comets.
We have compared these model assumptions
to observational results of sungrazing comets as well as to findings from space measurements. We have further
implemented this model in studies of the light scattering properties of dust to explain astronomical
observations.
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