Ice aggregate contacts at the nm-scale

Abstract

Aggregation of ice particles is a fundamental process in the interstellar medium as well as in planet formation. Dedicated to study the contact physics of nm-ice particles we developed a thermal gradient force microscope. This allows us and was used to measure pull-off forces with a resolution on the nN-scale and to measure rolling. Furthermore, based on a free probe, it also allows us to study twisting torques for the first time. The experiments show that torques required to twist are significantly larger than that macroscopic models scaled down to the nm-size range would predict. This implies that (ice) aggregates in astrophysical settings with small constituents are more robust against restructuring than previously thought. They likely grow as fractal aggregates to larger size before they restructure and during later compact growth they likely retain a higher porosity during further evolution towards planetesimals.

15 pages, 16 figures, accepted MNRAS

References in corpus (10)

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• Contacts of Water Ice in Protoplanetary Disks - Laboratory Experiments
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• Collisions of CO${}_2$ Ice Grains in Planet Formation
• Ice Grain Collisions in Comparison: CO${}_2$, H${}_2$O and their Mixtures
• How dust fragmentation may be beneficial to planetary growth by pebble accretion
• Understanding planet formation using microgravity experiments
• Dust evolution and satellitesimal formation in circumplanetary disks
• Is There a Temperature Limit in Planet Formation at 1000 K?
• The footprint of cometary dust analogs: I. Laboratory experiments of low-velocity impacts and comparison with Rosetta data
• Are Pebble Pile Planetesimals Doomed?
• Onset of planet formation in the warm inner disk -- Colliding dust aggregates at high temperatures
• Planetesimal formation via the streaming instability in simulations of infall dominated young disks
• Selective Aggregation Experiments on Planetesimal Formation and Mercury-Like Planets