A SEARCH FOR SMALL KUIPER BELT OBJECTS BY STELLAR OCCULTATIONS

摘要

We report the conditions and results of an observation campaign organized in 2000 September at the Pic du Midi Observatory, and dedicated for the first time to the study of Kuiper belt objects (KBOs) by stellar occupations. The observation consisted of recording the flux of a well-chosen star with a fast photometer (20 Hz) and counting occultations of this star by passing KBOs. The campaign provided 15 hr of good-quality signal (rms σ ～ 1.8%) and zero detections of KBOs at a 4 σ detection level. For a KBO differential size distribution assumed to vary as r~(-q), this first result suggests a slope q approx< 4.5. A refined analysis of the data, studying diffraction patterns, allowed us to find an event at a 3 σ detection level compatible with a 150 m KBO. More generally, observation campaigns of stellar occultation by KBOs on ≥2 m class telescopes could statistically constrain the slope and the expected turnover radius due to collisional erosion of the subkilometer KBO size distribution.