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Over the past years the processes involved in the growth of planetesimals have extensively been studied in the laboratory. Based on these experiments, a dust-aggregate collision model was developed upon which computer simulations were based…
For dust aggregates in protoplanetary discs a transition between sticking and bouncing in individual collisions at mm to cm size has been observed in the past. This lead to the notion of a bouncing barrier for which growth gets stalled.…
We conducted micro-gravity experiments to study the outcome of collisions between sub-mm-sized dust agglomerates consisting of \mu m-sized SiO2 monomer grains at velocities of several cm/s. Prior to the experiments, we used X-ray computer…
Understanding the collisional behavior of dust aggregates is essential in the context of planet formation. It is known that low-velocity collisions of dust aggregates result in bouncing rather than sticking when the filling factor of…
The collision outcomes of dust aggregates in protoplanetary disks dictate how planetesimals form. Experimental and numerical studies have suggested that bouncing collisions occurring at low impact velocities may limit aggregate growth in…
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…
To study the evolution of protoplanetary dust aggregates, we performed experiments with up to 2600 collisions between single, highly-porous dust aggregates and a solid plate. The dust aggregates consisted of spherical SiO$_2$ grains with…
In laboratory experiments, we studied collisions of ensembles of compact (filling factor 0.33) millimeter dust aggregates composed of micrometer quartz grains. We used cylindrical aggregates, triangular aggregates, square aggregates, and…
Context: Bouncing collisions of dust aggregates within the protoplanetary may have a significant impact on the growth process of planetesimals. Yet, the conditions that result in bouncing are not very well understood. Existing simulations…
For the investigation of collisions among protoplanetesimal dust aggregates, we performed microgravity experiments in which the impacts of high-porosity mm-sized dust aggregates into 2.5 cm-sized high-porosity dust aggregates can be…
We performed micro-gravity collision experiments in our laboratory drop-tower using 5-cm-sized dust agglomerates with volume filling factors of 0.3 and 0.4, respectively. This work is an extension of our previous experiments reported in…
Aggregation of dust through sticking collisions is the first step of planet formation. Basic physical properties of the evolving dust aggregates strongly depend on the porosity of the aggregates, e.g. mechanical strength, thermal…
The sticking of micron sized dust particles due to surface forces in circumstellar disks is the first stage in the production of asteroids and planets. The key ingredients that drive this process are the relative velocity between the dust…
The collisional and sticking properties of sub-mm-sized aggregates composed of protoplanetary dust analogue material are measured, including the statistical threshold velocity between sticking and bouncing, their surface energy and tensile…
The current model of planet formation lacks a good understanding of the growth of dust particles inside the protoplanetary disk beyond mm sizes. In order to investigate the low-velocity collisions between this type of particles, the…
Collisional evolution is a key process in planetesimal formation and decimetre bodies play a key role in the different models. However, the outcome of collisions between two dusty decimetre bodies has never been studied experimentally.…
The formation of planetesimals in the early Solar System is hardly understood, and in particular the growth of dust aggregates above millimeter sizes has recently turned out to be a difficult task in our understanding [Zsom et al. 2010,…
It is unknown how far dust growth can proceed by coagulation. Obstacles to collisional growth are the fragmentation and bouncing barriers. However, in all previous simulations of the dust-size evolution in protoplanetary disks, only the…
The experiments presented aim to measure the outcome of collisions between sub-mm sized protoplanetary dust aggregate analogues. We also observed the clusters formed from these aggregates and their collision behaviour. The experiments were…
In a protoplanetary disk, dust aggregates in the $\mu$m to mm size range possess mean collision velocities of 10 to 60 ms$^{-1}$ with respect to dm- to m-size bodies. We performed laboratory collision experiments to explore this parameter…