Exo-Kuiper belts in scattered light

Séminaire IPAG de Julien Milli (IPAG), jeudi 5 novembre 2020, 11h00, IPAG seminar room

Exo-Kuiper belts are belts of planetesimals orbiting at a few tens of astronomical units around main-sequence stars. Depending on their collisional activity, they can produce copious amount of dust particles that re-emit in the infrared. This thermal emission has been used to track their presence and to show that there are very common, with an occurence rate higher than 20%. Optical and near-infrared images at high-angular resolution reveal the light scattered by the micron-sized dust particles. It is a precious observable to study the dynamics of the planetary system and study remotely the building blocks of planets. Extreme adaptive optics instruments, such as SPHERE at the VLT have revealed exquisite details on those systems, allowing to extract their morphology and the scattering phase function of the dust particles in unpolarised or polarised light. The phase function is a powerful diagnostic tool to understand the physical properties of those particles, especially their structure and size. This suggests we are observing fluffy aggregates rather than compact dust grains. In this seminar, I will present the instrumental challenges to study those systems in scattered light and focus on what we can learn when extracting the dust optical properties.