Probing exoplanetary materials using sublimating dust

Planetary systems consist of more than just planets orbiting a central star. They also include a wide range of smaller bodies, such as asteroids, comets, and interplanetary dust grains. All these materials can be investigated to increase our understanding of planetary systems. In the study of extrasolar systems, the dust component can be particularly useful, because it constitutes a relatively large cross-section, making it observationally accessible to modern telescopes.
To correctly make the step from dust observations to inferring properties of an exoplanetary system, one must understand in detail how dust grains are produced, how they behave after being released, and how they are destroyed or removed. Understanding the physics of circumstellar dust is the subject of my thesis work. The thesis focusses specifically on dust grains orbiting extremely close to their host star, at only a few stellar radii, where temperatures can be reached that are sufficient to sublimate rocks.
I studied two astrophysical problems in which dust sublimation is relevant. (1) Hot exozodiacal dust. This is dust located in the close vicinity of a star that can be detected through near-infrared interferometry. Some 10% to 30% of all stars seem to have such a population of dust, but its origin is still unclear. I tested possible mechanisms that could explain the phenomenon, and made an in-depth study of the inner parts of the Fomalhaut system. (2) Dusty tails of evaporating exoplanets. I demonstrated how the composition of dust released by an evaporating rocky exoplanet, which trails the planet in a comet-like tail, can be inferred from detailed shape of the transit light curve produced by these objects.