Planet formation occurs in protoplanetary disks composed of gas, dust and ice. Dust aggregation is a critical step in planet formation, but dust on its own is not very sticky. Models and experiments suggest that water can act as a "glue" in the planet-making process. Scientists from The Open University and Technical University Braunschweig, in collaboration with disordered materials group, used neutron scattering and cryo-SEM (scanning electron microscopy) to study the structural properties of tiny icy particles, to gain insight into planet formation.

The unique capabilities of NIMROD allowed the team to simultaneously characterise the bulk and surface structure of the micrometre-sized icy particles, and investigate structural changes with temperature. Their results, published in The Astrophysical Journal, have important implications for planet formation. Planet formation models currently prioritise parameters such as particle size and velocity, but the results from this study suggest that the surface pre-melting process plays a crucial role in collision experiments. The pressure-temperature environment may, therefore, have a more significant effect on collision outcomes than previously thought. Further investigations are required so that the influence of ice physics on the outcome of collisions can be included in more sophisticated models of planet formation. 

Related publication: “Micrometer-sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties" The Astrophysical Journal, Volume 848, Number 2, DOI: 10.3847/1538-4357/aa8c7

Authors: S. Gärtner (The Open University), B. Gundlach (TU Braunschweig), T. F. Headen (ISIS), J. Ratte (TU Braunschweig), J. Oesert (Christian-Albrechts-Universität zu Kiel), S. N. Gorb (Christian-Albrechts-Universität zu Kiel), T. G. A. Youngs (ISIS), D. T. Bowron (ISIS), J. Blum (TU Braunschweig), and H. J. Fraser (The Open University).

Instrument: NIMROD​