Detection of exozodiacal dust: a step toward Earth-like planet characterization with infrared interferometry

The existence of other habitable worlds and the possible development of life elsewhere in the Universehave been among mankind’s fundamental questions for thousands of years. These interrogations aboutour origins and place in the Universe are today at the dawn of being answered in scientific terms. Thekey year was 1995 with the discovery of the first extrasolar planet orbiting around a solar-type star.About 400 extrasolar planets are known today and the possibility to identify habitable worlds and evenlife among them largely contributes to the growing interest about their nature and properties. However,characterizing planetary systems is a very difficult task due to both the huge contrast and the smallangular separation between the host stars and their environment. New techniques have emerged duringthe past decades with the purpose of tackling these fantastic observational challenges. In that context,infrared interferometry is a very promising technique, since it provides the required angular resolution toseparate the emission of the star from that of its environment.This dissertation is devoted to the characterization of extrasolar planetary systems using the highangular resolution and dynamic range capabilities of infrared interferometric techniques. The first partof the present work is devoted to the detection with current interferometric facilities of warm dust withinthe first few astronomical units of massive debris discs around nearby stars. In order to extend theimaging of planetary systems to fainter discs and to extrasolar planets, we investigate in a second stepthe performance of future space-based nulling interferometers and make a comparison with ground-basedprojects. Finally, the third part of this work is dedicated to the impact of exozodiacal discs on theperformance of future life-searching space missions, the goal being to characterize extrasolar planets withsizes down to that of the Earth.