A near-infrared interferometric survey of debris-disk stars
1 Univ. Grenoble Alpes, IPAG, 38000 Grenoble, France
2 CNRS, IPAG, 38000 Grenoble, France
3 European Southern Observatory, Alonso de Cordova 3107, Vitacura, 19001 Casilla, Santiago 19, Chile
4 Département d’Astrophysique, Géophysique et Océanographie, Université de Liège, Allée du Six Août 17, 4000 Liège, Belgium
5 Department of Astronomy, University of Arizona, 993 N. Cherry Ave, Tucson, AZ 85721, USA
6 Max-Planck Institute for Extraterrestrial Physics, Gießenbachstraße, 85741 Garching, Germany
7 School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
8 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
9 Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
10 NASA Exoplanet Science Institute, California Institute of Technology, 770 S. Wilson Ave., Pasadena, CA 91125, USA
Received: 19 June 2014
Accepted: 9 September 2014
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 searched a magnitude-limited (H ≤ 5) sample of 92 stars for bright exozodiacal dust using our VLTI visitor instrument PIONIER in the H band. We derived 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 derived 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 allowed us to put constraints on the emission mechanism and the dust properties in the detected systems.
Results. We find an overall 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.
Key words: techniques: interferometric / circumstellar matter / planetary systems / zodiacal dust
Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 089.C-0365 and 090.C-0526.
Appendix A and Table 1 are available in electronic form at http://www.aanda.org
© ESO, 2014