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CO2-ice in the context of planet formation

Applicant Dr. Jens Teiser
Subject Area Astrophysics and Astronomy
Term from 2018 to 2025
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 413220058
 
Final Report Year 2023

Final Report Abstract

The goal of the proposed project was to study collisions of CO2-ice agglomerates to provide crucial input for numerical collision simulations, interpretation of astronomical observations or, more general, for planet formation models. In contrast to previous studies this project used well-defined CO2-ice particles and agglomerates. Different experiment methods and setups were developed for their generation, starting with a method to generate micrometer-size CO2 particles. An experiment facility was designed and built to investigate collisions of sub-millimeter CO2 agglomerates with collision velocities up to 3.4 m/s. The threshold velocity for direct sticking is 0.07 m/s, bouncing at larger velocities. The fragmentation threshold for agglomerate sizes of around 30 µm the fragmentation threshold was found at around 1 m/s. Additionally, the tensile strength of cylindrical CO2 agglomerates was measured - also in a new setup - depending on the volume filling allowing a measurement of the surface energy. This way, the surface energy was measures for the first time as = (0.060 ± 0.022) J/m2 . Altogether, the experiments showed that CO2 ice behaves like silicate dust of the same size range. Therefore, all known growth possibilites but also barriers such as the bouncing barrier or the fragmentation barrier apply and the existing models for particle evolution in disks can be used.

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