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The thesis deals with the first stage of planet formation, namely dust coagulation from micron to millimeter sizes in circumstellar disks. For the first time, we collect and compile the recent laboratory experiments on dust aggregates into…
Investigating the dynamical evolution of dust grains in proto-planetary disks is a key issue to understand how planets should form. We identify under which conditions dust settling can be constrained by high angular resolution observations…
In order to characterize the early growth of fine-grained dust rims (FGRs) that commonly surround chondrules, we perform numerical simulations of dust accretion onto chondrule surfaces. We employ a Monte Carlo algorithm to simulate the…
Before Rosetta, the space missions Giotto and Stardust shaped our view on cometary dust, supported by plentiful data from Earth based observations and interplanetary dust particles collected in the Earth's atmosphere. The Rosetta mission at…
Context: In protoplanetary discs, micron-sized dust grows to form millimetre- to centimetre-sized pebbles but encounters several barriers during its evolution. Collisional fragmentation and radial drift impede further dust growth to…
Context: The dust-brightness phase curves that have been measured by the OSIRIS cameras on board the Rosetta spacecraft within the coma of comet 67P/Churyumov-Gerasimenko (67P) present a remarkable u-shape. Aims: Our goal is to compare…
Dust particles are the building blocks from which planetary bodies are made. A major goal of the studies of planet-forming disks is to constrain the properties of dust particles and aggregates in order to trace their origin, structure, and…
Aims: The aim of this work is to gain a deeper insight into how much different aggregate types are affected by erosion. Especially, it is important to study the influence of the velocity of the impacting projectiles. We also want to provide…
Context: In protoplanetary disks, dust grains coagulate with each other and grow to form aggregates. As these aggregates grow by coagulation, their filling factor \phi decreases down to \phi << 1. However, comets, the remnants of these…
The porosity of an asteroid is important when studying the evolution of our solar system through small bodies and for planning mitigation strategies to avoid disasters due to asteroid impacts. Our knowledge of asteroid porosity largely…
In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to…
ALMA observations of protoplanetary disks confirm earlier indications that there is a clear difference between the dust and gas radial extents. The origin of this difference is still debated, with both radial drift of the dust and optical…
Porosity evolution of dust aggregates is crucial in understanding dust evolution in protoplanetary disks. In this study, we present useful tools to study the coagulation and porosity evolution of dust aggregates. First, we present a new…
Collisions between centimeter- to decimeter-sized dusty bodies are important to understand the mechanisms leading to the formation of planetesimals. We thus performed laboratory experiments to study the collisional behavior of dust…
In dense molecular clouds collisions between dust grains alter the ISM-dust size distribution. We study this process by inserting the results from detailed numerical simulations of two colliding dust aggregates into a coagulation model that…
The structure and mechanical properties of a simple two-dimensional model of a cohesive powder are investigated by molecular dynamics simulations. Micromechanical ingredients involve elasticity, friction, a short range attraction and,…
Context. Particle trapping in local or global pressure maxima in protoplanetary disks is one of the new paradigms in the theory of the first stages of planet formation. However, finding observational evidence for this effect is not easy.…
We study the surface growth generated by the random deposition of particles of different sizes. A model is proposed where the particles are aggregated on an initially flat surface, giving rise to a rough interface and a porous bulk. By…
The evolution of protoplanetary disks, especially in the early stages of planetary formation, as dust grows, is the cornerstone of the birth of planets. The mechanisms involved in the growth of sub-micrometric dust grains into planetesimals…
Combining a particle-particle, particle-cluster and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in various plasma environments relevant for proto-planetary disks have…