First evidence for a resolved structure in the inner Vega system

We report on infrared interferometric observations of Vega obtained in May and June 2005 with the FLUOR instrument installed on the CHARA interferometer. The combination of short and long baselines has allowed us to study the brightness distribution of the stellar photosphere, and to detect a spatial component which is over-resolved at our lowest resolution (~15 milli-arcseconds). This would be attributed to structure much larger than Vega, but within the CHARA/FLUOR field-of-view (about 1 arcsecond in radius, i.e., 8 AU around Vega). The contrast between the resolved flux and the central star is only slightly above the 1% level in K band. This emission could be interpreted as the first direct detection of thermal and/or scattered light emanating from the innermost part of the Vega debris disk, which is thought to be continuously replenished by asteroid collisions and/or comet evaporation. The possibility of a close stellar or sub-stellar companion is also investigated.