2012A&A...546L...9D

We aim at resolving the circumstellar environment around {beta} Pic in the near-infrared in order to study the inner planetary system (<200mas, i.e., ∼4AU). Precise interferometric fringe visibility measurements were obtained over seven spectral channels dispersed across the H band with the four-telescope VLTI/PIONIER interferometer. Thorough analysis of interferometric data was performed to measure the stellar angular diameter and to search for circumstellar material. We detected near-infrared circumstellar emission around {beta} Pic that accounts for 1.37%±0.16% of the near-infrared stellar flux and that is located within the field-of-view of PIONIER (i.e., ∼200mas in radius). The flux ratio between this excess and the photosphere emission is shown to be stable over a period of 1 year and to vary only weakly across the H band, suggesting that the source is either very hot (>1500K) or dominated by the scattering of the stellar flux. In addition, we derive the limb-darkened angular diameter of {beta} Pic with an unprecedented accuracy (θ_LD=0.736±0.019mas). The presence of a small H-band excess originating in the vicinity of {beta} Pic is revealed for the first time thanks to the high-precision visibilities enabled by VLTI/PIONIER. This excess emission is likely due to the scattering of stellar light by circumstellar dust and/or the thermal emission from a yet unknown population of hot dust, although hot gas emitting in the continuum cannot be firmly excluded.