The inner regions of protoplanetary disks

The inner regions of protoplanetary disks are where terrestrial planets and super-Earths form and/or migrate to. We investigate the dust in these regions as the base material for planet formation.
Pre-transitional disks show a strong NIR-excess from an inner dust disk. In Chapter 2 we explore how this disk is sustained over several million years even if a gap prevents outer disk grains from replenishing accreted material.
In Chapter 3 we investigate the inner region of transitional disks with PIONIER NIR-interferometry. With HD 100453 as a benchmark case, we show that extended NIR-emission in Herbig disks is created by quantum-heated, very small carbonaceous grains and that we can constrain their amount, size and spatial distribution.
Interferometric observations are often interpreted using simplified flux components. In Chapter 4 we study how these results relate to the structure of the inner disk. The inner rim position is very well constrained, and the radial extent of the rim to within a factor of two. We find that the rim position of most Herbig stars can be modeled using olivine grains with power-law size distribution or by using highly refractory grains.
The refractory carbon-to-silicon fraction in the Earth is significantly lower than in the interstellar medium. In Chapter 5 we examine if photolysis and oxidation in the exposed upper disk layers can remove refractory carbon before parent-body formation. Especially radial dust transport limits the removal efficiency. More efficient carbon removal mechanisms need to be studied, combined with strongly reduced grain mobility.