Collisions of solid ice in planetesimal formation

Abstract

We present collision experiments of centimetre projectiles on to decimetre targets, both made up of solid ice, at velocities of 15 m s −1 to 45 m s −1 at an average temperature of T avg = 255.8 ± 0.7 K. In these collisions the centimetre body gets disrupted and part of it sticks to the target. This behaviour can be observed up to an upper threshold, that depends on the projectile size, beyond which there is no mass transfer. In collisions of small particles, as produced by the disruption of the centimetre projectiles, we also find mass transfer to the target. In this way the larger body can gain mass, although the efficiency of the initial mass transfer is rather low. These collision results can be applied to planetesimal formation near the snowline, where evaporation and condensation is expected to produce solid ice. In free fall collisions at velocities up to about 7 m s −1 , we investigated the threshold to fragmentation and coefficient of restitution of centimetre ice spheres.

Size and density sorting of dust grains in SPH simulations of protoplanetary discs – II. Fragmentation

“…However, to date, there is no unified theoretical framework which can be used to extrapolate unknown fragmentation properties of aggregates of different size and species. Nevertheless, there is a large spread of values for fragmentation thresholds for different types of dusty grains that range from 1 m s −1 to 50 m s −1 (Blum & Wurm 2008;Wada et al 2009;Teiser & Wurm 2009;Zsom et al 2010;Wada et al 2013;Meru et al 2013;Yamamoto et al 2014;Deckers & Teiser 2016). Fragmentation can constitute a crucial problem in the framework of planet formation.…”

ICE GRAIN COLLISIONS IN COMPARISON: CO2, H2O, AND THEIR MIXTURES

“…Planet formation in general, but especially collisional outcomes, are tied to these icelines and the physics of the prevailing kind of ice. (Aumatell & Wurm 2011Ali-Dib et al 2014;Blum et al 2014;Deckers & Teiser 2016;Musiolik et al 2016).…”

Micrometer-sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties

“…However, previous experiments (Bridges et al 1984;Hatzes et al 1988;McDonald et al 1989;Hatzes et al 1991;Supulver et al 1995;Dilley & Crawford 1996;Higa et al 1996;Bridges et al 1996;Higa et al 1998;Heißelmann et al 2010;Shimaki & Arakawa 2012b,a;Hill et al 2015;Gundlach & Blum 2015;Deckers & Teiser 2016;Musiolik et al 2016) disagree on whether, and how, varies as a function of temperature, pressure, velocity, size, and shape. The question is, why is this?…”

“…Micrometer-sized particles can be created by shattering larger bodies of ice prepared in a freezer (Deckers & Teiser 2016), or by rapid freezing of water droplets e.g. on cold surfaces (Musiolik et al 2016) or by introducing them into a cold gaseous or liquid environments (Gundlach & Blum 2015;Shimaki & Arakawa 2012a), However, without further characterization, we cannot know whether, and how, the production alters the particle structure on all length-scales, exactly which form of crystalline ice is produced, and to what extend the P -T conditions of the collision environment influence the collisional outcomes.…”

“…Bridges et al 1984;Deckers & Teiser 2016), including ours (e.g. Gundlach & Blum 2015;Hill et al 2015), must have been colliding crystalline ice particles, as no method has yet been reported to effectively produce amorphous particles suitable for collision experiments.…”