Growth beyond the meter-barrier: Aggregation and fragmentation in single and multiple high velocity collisions

在星子的碰撞生长中，一个尚未解决的问题是通常被称为“米屏障”的问题。原行星盘的模型表明，一米大小的天体以几十米/秒的速度与较小的天体相撞。通过碰撞形成星子只有在具有质量增益的高速碰撞胜过破坏性或侵蚀性碰撞的情况下才有可能。上述项目的实验室实验表明，典型的分米级体为米级体的前身，是具有独特孔隙率的致密粉尘集合体。与如此致密的尘埃聚集体的碰撞表明，低于毫米的聚集体可能以超过50米/秒的高速为较大的物体增加质量。然而，大于毫米的弹丸会对目标造成侵蚀。详细地说，破碎/凝固模型是形成更大体的可行途径。对于这种模型来说，不同参数和给定碰撞速度的弹丸的质量平衡和碎片大小是必不可少的。该项目旨在测量单个但特别是多次高速碰撞的结果，以模拟星子的生长，以跨越米障。

An unsolved problem in collisional growth of planetesimals is the often-called meterbarrier. Models of protoplanetary disks suggest that meter sized bodies collide with smaller bodies at velocities of several tens of m/s. Forming planetesimals by collisions is only possible if collisions at high speed with mass gain win over destructive or eroding collisions. The laboratory experiments in the preceeding project showed that a typical decimeter body as progenitor to meter size bodies is a compact dust aggregate with a unique porosity. Collisions with such a compact dust aggregate suggest that sub-mm aggregates might add mass to a larger body at high speed even beyond 50m/s. However, projectiles larger than mm lead to erosion of a target. In detail, a fragmentation / coagulation model is a viable path to form larger bodies. For such a model the mass balance and fragment sizes for projectiles of varying parameters and for given collisions velocities are essential. The project aims at measuring the outcome of individual but especially multiple high speed collisions to model the growth of planetesimals to bridge the meter-barrier.