A near-infrared interferometric survey of debris-disc stars. IV. An unbiased sample of 92 southern stars observed in H-band with VLTI/PIONIER

TL;DR

This study surveys 92 nearby stars using VLTI/PIONIER to detect hot exozodiacal dust, revealing an 11% detection rate and insights into dust properties and their relation to stellar characteristics, aiding future planet imaging efforts.

Contribution

First comprehensive H-band interferometric survey of 92 stars for hot exozodiacal dust, providing new statistics and constraints on dust properties and correlations with stellar parameters.

Findings

11% detection rate of hot exozodiacal dust.

Detection rate decreases from early to late type stars.

Dust emission likely dominated by scattered light or extremely hot dust.

Abstract

Context. Detecting and characterizing circumstellar dust is a way to study the architecture and evolution of planetary systems. Cold dust in debris disks only traces the outer regions. Warm and hot exozodiacal dust needs to be studied in order to trace regions close to the habitable zone. Aims. We aim to determine the prevalence and to constrain the properties of hot exozodiacal dust around nearby main-sequence stars. Methods. We search a magnitude limited (H < 5) sample of 92 stars for bright exozodiacal dust using our VLTI visitor instrument PIONIER in the H-band. We derive statistics of the detection rate with respect to parameters such as the stellar spectral type and age or the presence of a debris disk in the outer regions of the systems. We derive more robust statistics by combining our sample with the results from our CHARA/FLUOR survey in the K-band. In addition, our spectrally dispersed data allows us to put constraints on the emission mechanism and the dust properties in the detected systems. Results. We find an over-all detection rate of bright exozodiacal dust in the H-band of 11% (9 out of 85 targets) and three tentative detections. The detection rate decreases from early type to late type stars and increases with the age of the host star. We do not confirm the tentative correlation between the presence of cold and hot dust found in our earlier analysis of the FLUOR sample alone. Our spectrally dispersed data suggest that either the dust is extremely hot or the emission is dominated by the scattered light in most cases. The implications of our results for the target selection of future terrestrial planet finding missions using direct imaging are discussed.