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

该项目的目标是继续在Forschergruppe项目“高温尘埃碰撞实验”第一阶段开始的实验研究，并将其扩展到分析在高温影响下可能对（原）星子的演化起重要作用的进一步过程。我们将在高达1300 K的温度下进行碰撞实验，实验装置是在Forschergruppe的第一阶段建造的。因此，我们预计由于烧结和共晶熔化等现象的发生，碰撞和粘附行为会发生重大变化。所利用的原行星尘埃类似物将包括真实的单矿物尘埃样本和矿物混合物以及焦油和沥青等有机材料。除此之外，我们还将继续测量各种材料的导热系数，这取决于孔隙率和烧结阶段。由此得到的信息将显示放射性加热和其他热源能在多大程度上导致星子熔化或烧结，从而改变它们的内部结构。此外，我们将根据组成碰撞伙伴的烧结等级确定先前烧结的粉尘聚集体在低速碰撞实验中的粘附概率。研究结果将揭示由于烧结过程，骨料的凝固如何影响粘结、弹跳和破碎的障碍，并最终影响有效生长过程。对这些高温过程的研究可能会揭示出相关的机制，以解释有关原星子生长超过临界尺寸和碰撞速度的未解决问题。

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.