After 25 years of laboratory research on protoplanetary dust agglomeration, a consistent picture of the various processes that involve colliding dust aggregates has emerged. Besides sticking, bouncing and fragmentation, other effects, like, e.g., erosion or mass transfer, have now been extensively studied. Coagulation simulations consistently show that μm$\upmu\mbox{m}$-sized dust grains can grow to mm- to cm-sized aggregates before they encounter the bouncing barrier, whereas sub-μm$\upmu\mbox{m}$-sized water-ice particles can directly grow to planetesimal sizes. For siliceous materials, other processes have to be responsible for turning the dust aggregates into planetesimals. In this article, these processes are discussed, the physical properties of the emerging dusty or icy planetesimals are presented and compared to empirical evidence from within and without the Solar System. In conclusion, the formation of planetesimals by a gravitational collapse of dust “pebbles” seems the most likely.

中文翻译：

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原行星盘中的尘埃演化和小行星的形成

经过 25 年对原行星尘埃聚集的实验室研究，已经出现了涉及碰撞尘埃聚集的各种过程的一致画面。除了粘连、弹跳和破碎之外，其他影响，例如侵蚀或传质，现在已经得到广泛研究。凝结模拟一致表明，μm$\upmu\mbox{m}$ 大小的尘埃颗粒在遇到弹跳屏障之前可以长成毫米到厘米大小的聚集体，而亚μm$\upmu\mbox{m}$-大小的水冰颗粒可以直接增长到行星的大小。对于硅质材料，其他过程必须负责将尘埃聚集体变成微行星。在本文中，讨论了这些过程，呈现出正在出现的尘土飞扬或冰冷的小行星的物理特性，并与来自太阳系内外的经验证据进行比较。总之，由尘埃“卵石”的引力坍缩形成微星的可能性似乎最大。