Experiments on centimeter-sized dust aggregates and their implications for planetesimal formation
Experiments on centimeter-sized dust aggregates and their implications for planetesimal formation
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DOI：
10.1051/0004-6361/201219099
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发表时间：
2012-07
影响因子：
6.5
通讯作者：
Thorsten Meisner;J. Teiser;G. Wurm
中科院分区：
文献类型：
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作者：
Thorsten Meisner;J. Teiser;G. Wurm
原行星盘中的第一个宏观天体是尘埃聚集体。我们报告了一些实验研究与粉尘聚集体形成微米级石英颗粒。我们证实在实验室碰撞实验中的早期发现，产生宏观机构的随机影响的亚毫米骨料的结果在一个定义良好的上填充因子为0.31 \pm 0.01。与早期的实验相比，我们将抛射体质量增加了约100倍。碰撞实验还表明，一个高度多孔的尘埃聚集体可以保留其高度多孔的核心，如果碰撞得到更大的能量和更密集的外壳上的多孔核心的形式。我们测量的机械性能的厘米大小的粉尘样品的不同填充因子之间的0.34和0.50。通过巴西试验测量的拉伸强度在1 kPa和6 kPa之间变化。声速由运行时间测量确定，范围在80 m/s和140 m/s之间，而杨氏模量由声速得出，并在7 MPa和25 MPa之间变化。对试样进行了准静态全方位和单向压缩，以确定其压缩强度和流动函数。应用于行星形成，我们的实验为未来的模拟提供了基本数据，解释了在早期实验中观察到的具体碰撞结果，并在一般情况下支持碰撞的星子增长是可能的。
The first macroscopic bodies in protoplanetary disks are dust aggregates. We report on a number of experimental studies with dust aggregates formed from micron-size quartz grains. We confirm in laboratory collision experiments an earlier finding that producing macroscopic bodies by the random impact of sub-mm aggregates results in a well-defined upper-filling factor of 0.31 \pm 0.01. Compared to earlier experiments, we increase the projectile mass by about a factor of 100. The collision experiments also show that a highly porous dust-aggregate can retain its highly porous core if collisions get more energetic and a denser shell forms on top of the porous core. We measure the mechanical properties of cm-sized dust samples of different filling factors between 0.34 and 0.50. The tensile strength measured by a Brazilian test, varies between 1 kPa and 6 kPa. The sound speed is determined by a runtime measurement to range between 80 m/s and 140 m/s while Young's modulus is derived from the sound speed and varies between 7MPa and 25MPa. The samples were also subjected to quasi-static omni- and uni-directional compression todetermine their compression strengths and flow functions. Applied to planet formation, our experiments provide basic data for future simulations, explain the specific collisional outcomes observed in earlier experiments, and in general support a scenario where collisional growth of planetesimals is possible.