Dynamics and Erosion of Solids in Protoplanetary Disks



Protoplanetary disks are the natural by-product of star formation and the sites of planet formation. They are composed of gas and solids with sizes that range between micrometer and kilometer scales. The interaction between this material is complex and understanding its details is key for a complete picture on planet formation.

Today, we have several tools available, which can put constraints on the theory of planet formation. One such tool is observations of protoplanetary disks, which amongst other things have given us high resolution images of the early stages of planet formation and showed us that disks host complex substructures. Another key tool is missions with the goal of understanding our own Solar System. An excellent example of this is New Horizons, which through a fly-by of the Kuiper belt object, Arrokoth, confirmed that planets form through gentle clumping as opposed to violent collisions. Laboratory experiments that aim to recreate protoplanetary disk conditions has shown us that the growth of the smallest disk solids is not as straight-forward as previously thought, such that direct growth to larger solids only works in some cases. Finally, we have numerical simulations, which are a powerful tool as well, since they are not limited by physical conditions that often hinder observations and experiments.

This thesis is focused on the early stages of the planet formation process. The workpresented here relies on computer simulations, which we use to build models on the interaction between the protoplanetary disk gas and solids. Following what observations and laboratory experiments have revealed, we incorporate the co-existence of a range of solid sizes in our models. We show that the dynamics of the system is altered by the interactions of the solids of various sizes through the gas. We also find that the inclusion of the realistic case of multiple solid sizes successfully produces the solid clumps necessary for the next stage of the planet formation process.

In this thesis, we also study how the interaction between the disk gas and the solids can be destructive as well. More specifically, we focus on understanding how significant gas erosion is for solids. In general, we find that solids in the inner disks can survive erosion only if they are on nearly circular orbits.
Gällande start-/slutdatum2015/10/012021/04/29