Hot dust in the inner parts of circumstellar debris discs

Studying the warm inner part of debris discs—the extrasolar counterparts of the zodiacal dust cloud—is of prime importance to characterize the global architecture of planetary systems. Because of the high contrast and small angular separation between the star and the exozodiacal light, high-precision infrared interferometry is the best-suited tool to carry out such observations. In this paper, we review the first direct detection of an exozodiacal disc recently reported around Vega by Absil et al. (2006), and discuss the currently on-going observing efforts in this domain. We show how interferometric data can constrain the composition and the dynamics of extrasolar planetary systems, and thereby put useful constraints on the presence of small bodies and/or giant planets. First statistical trends for high-density exozodiacal discs towards a small sample of nearby main sequence stars are presented. Finally, we briefly discuss how next generation interferometric instruments could change our view of debris discs, pushing the detection limit towards meaningful density levels in the context of future life-finding missions such as Darwin/TPF.