Where are the crystals? Studying the distribution of silicates in planet-forming disks with VLTI/MATISSE
Silicate dust grains constitute the major part of the building blocks of terrestrial planets. They come in two flavours: the amorphous (glassy) grains originally present in the interstellar medium, and the crystalline grains formed in situ in planet-forming disks. By studying the spatial distribution of these grains within the disks we can trace the earliest stages of planet formation. Mid-infrared interferometric observations revealed that in some disks the inner parts had larger fractions of crystalline grains, while the outer parts were composed of predominantly small amorphous grains. This indicates that crystalline grains form in the inner disk (within ~1 au) where the temperature is high enough. However, radial mineralogy gradients are still not well characterized, and crystalline grains are frequently found in outer disks. I will present new observations of the silicate dust in selected planet-forming disks with VLTI/MATISSE, with the aim to consistently model the disk geometry and dust distribution. An interesting question is the potential influence of disk substructures (rings, gaps) on radial mineralogy gradients.
