Contact forces between sub-micrometer ice particles in protoplanetary environments

• Applicant: Professor Dr. Gerhard Wurm
• Subject Area: Astrophysics and Astronomy
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 266114593

Research on planet formation saw a rapid evolution during the last few decades with respect to theory, observation and experiment. The first phases of planet formation are governed by collisions. It is the strength of the contacts between two particles, which decides if particles grow by sticking or are destroyed. Therefore, to quantify the interaction at the contact level is most fundamental for all further modeling of planet formation. Especially refractory materials like silicates were extensively studied in the laboratory so far. However, the outer regions of protoplanetary disks where cores of giant planets are supposed to be formed are dominated by water ice. The description of water ice contact physics on nanometer and micrometer size scale at low temperatures with application to planet formation only started recently and though very basic the underlying contact forces and torques are currently poorly known. Their measurement only recently became feasible by the development of a thermal gradient force microscope. In the proposed project we will establish this technique and carry out systematic measurements on nanometer to micrometer size water ice particle contacts. This will provide a first experimental database for modeling the early phases of icy planetesimal formation.

• DFG Programme: Research Grants