Free collisions in a microgravity many-particle experiment. I. Dust aggregate sticking at low velocities

By R. Weidling, C. Guttler, J. Blum. 2011

137 citations recorded by the source corpus.

Abstract Over the past years the processes involved in the growth of planetesimals have extensively been studied in the laboratory. Based on these experiments, a dust-aggregate collision model was developed upon which computer simulations were based to evaluate how big protoplanetary dust aggregates can grow and to analyze which kinds of collisions are relevant in the solar nebula and are worth further studies in the laboratory. The sticking threshold velocity of millimeter-sized dust aggregates is one such critical value that have so far only theoretically been derived, as the relevant velocities could not be reached in the laboratory. We developed a microgravity experiment that allows us for the first time to study free collisions of mm-sized dust aggregates down to velocities of ∼0.1 cm s −1 to assess this part of the protoplanetary dust evolution model. Here, we present the results of 125 free collisions between dust aggregates of 0.5–2 mm diameter. Seven collisions with velocities between 0.2 and 3 cm s −1 led to sticking, suggesting a transition from perfect sticking to perfect bouncing with a certain sticking probability instead of a sharp velocity threshold. We developed a model to explain the physical processes involved in dust-aggregate sticking, derived dynamical material properties of the dust aggregates from the results of the collisions, and deduced the velocity below which dust aggregates always stick. For millimeter-sized porous dust aggregates this velocity is 8 × 10 −5 m s −1 .

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0035737af04576955b5777d3e40fdd60fe7b9d1c

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In Astronomy and Astrophysics

Citations in the corpus

Breaking through: The effects of a velocity distribution on barriers to dust growth (2012, background): “With bouncing included (where both particles involved are kept unchanged), the sticking efficiency is written as ps = { 1 if v < vb 0 if v > vb, (2) where we take a bouncing threshold velocity vb = 5 cm/s, which is the upper limit to the bouncing threshold velocity found by Weidling et al. (2012).”
Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles (2017, background): “…m 1.58 × 10−3 m 5.00 × 10−3 m 1.58 × 10−2 m - Volume filling factor φpebble 0.4 Weidling et al. (2009); Güttler et al. (2010); Zsom et al. (2010) Young’s modulus Ypebble 8.1 × 103 Pa Weidling et al. (2012) Poisson ratio µpebble 0.17 Weidling et al. (2012) Water-ice properties Latent heat of…”