Preprint typeset using LATEX style emulateapj v. 08/13/06 CONFIRMING THE PRIMARILY SMOOTH STRUCTURE OF THE VEGA DEBRIS DISK AT MILLIMETER WAVELENGTHS

Clumpy structure in the debris disk around Vega has been previously reported at millimeter wave-lengths and attributed to concentrations of dust grains trapped in resonances with an unseen planet. However, recent imaging at similar wavelengths with higher sensitivity has disputed the observed structure. We present three new millimeter-wavelength observations that help to resolve the puzzling and contradictory observations. We have observed the Vega system with the Submillimeter Array (SMA) at a wavelength of 880µm and angular resolution of 5”; with the Combined Array for Re-search in Millimeter-wave Astronomy (CARMA) at a wavelength of 1.3mm and angular resolution of 5”; and with the Green Bank Telescope (GBT) at a wavelength of 3.3mm and angular resolution of 10”. Despite high sensitivity and short baselines, we do not detect the Vega debris disk in either of the interferometric data sets (SMA and CARMA), which should be sensitive at high significance to clumpy structure based on previously reported observations. We obtain a marginal (3σ) detection of disk emission in the GBT data; the spatial distribution of the emission is not well constrained. We analyze the observations in the context of several different models, demonstrating that the ob-servations are consistent with a smooth, broad, axisymmetric disk with inner radius 20-100AU an