Influence of high-temperature processes on the growth of protoplanetary dust aggregates and planetesimals

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The goal of this project is to continue the experimental investigations, which have begun in the first phase of the Forschergruppe in project with the title “High-temperature dust collision experiments”, as well as to extend them to the analysis of further processes that may play an important role for the evolution of (proto-)planetesimals under the influence of elevated temperatures. We will perform collision experiments at temperatures up to 1,300 K with the experimental setup constructed in phase 1 of the Forschergruppe. Thereby, we expect significant changes in the collision and adhesion behavior due to the occurrence of e.g. sintering and eutectic melting. The utilized protoplanetary dust analogs will comprise realistic mono-mineralic dust samples and mineral mixtures as well as organic materials like tar and asphalt. In addition to that, we will continue measurements to determine the thermal conductivity of various materials depending on the porosity and the sintering stage. The resulting information will show to what extent radioactive heating and other heat sources can lead to melting or sintering planetesimals and, thus, alter their internal structure. Furthermore, we will determine the sticking probability of previously sintered dust aggregates in low-velocity collision experiments depending on the sintering grade of the constituent collision partners. The results will reveal in what way the solidification of the aggregates, due to the sintering process, influences the barriers for sticking, bouncing and fragmentation and finally the effective growth process. The investigation of these high-temperature processes may indicate relevant mechanisms to explain unsolved questions pertaining to the growth of protoplanetesimals beyond critical sizes and collision velocities.