We present sensitive , sub-arcsecond resolution Submillimeter Array observations of the protoplanetary disk around the nearby , pre-main sequence spectroscopic binary V4046 Sgr .
We report for the first time a large inner hole ( r = 29 AU ) spatially resolved in the 1.3 mm continuum emission and study the structure of this disk using radiative transfer calculations to model the spectral energy distribution ( SED ) , continuum visibilities , and spectral line emission of CO and its main isotopologues .
Our modeling scheme demonstrates that the majority of the dust mass is distributed in a narrow ring ( centered at 37 AU with a FWHM of 16 AU ) that is \sim 5 \times more compact than the gas disk .
This structure implies that the dust-to-gas mass ratio has a strong spatial variation , ranging from a value much larger than typical of the interstellar medium ( ISM ) at the ring to much smaller than that of the ISM at larger disk radii .
We suggest that these basic structural features are potentially observational signatures of the accumulation of solids at a local gas pressure maximum .
These models also require a substantial population of \sim \mu m-sized grains inside the central disk cavity .
We suggest that this structure is likely the result of dynamical interactions with a low-mass companion , although photoevaporation may also play a secondary role .