High-sensitivity search for clumps in the Vega Kuiper-belt. New PdBI   1.3mm observations
  Previous studies have found that Vega is surrounded by an extended debris disc that is very smooth in the far infrared, but displays possible clumpiness at 850micron and dust emission peaks at 1.3mm. We reobserved Vega at 1.3mm with PdBI to constrain its circumstellar dust distribution. Our observations of a three-field mosaic have a factor of two higher sensitivity than previous observations. We detect Vega photosphere with the expected flux, but none of the previously reported emission peaks that should have been detected at the >6sigma level, with a sensitivity <1mK. This implies that the dust distribution around Vega is principally smooth and circularly symmetric. This also means that no planet is needed to account for dust trapped in mean-motion resonnance. 
Vincent Pi\'etu, Emmanuel Di Folco, St\'ephane Guilloteau,   Fr\'ed\'eric Gueth, Pierre Cox
astro-ph.SR