We present subarcsecond resolution dust continuum observations of the protostellar collapse candidate B335 made with the IRAM Plateau de Bure Interferometer at wavelengths of 1.2 and 3.0 mm .
These observations probe to < 100 AU size scales and reveal a compact source component that we identify with a circumstellar disk .
We analyze these data in concert with previous lower resolution interferometer observations and find a best fit density structure for B335 that consists of a power law envelope with index p = 1.55 \pm 0.04 ( r \lesssim 5000 AU ) together with a disk ( r < 100 AU ) of flux F _ { 1.2 \mathrm { mm } } = 21 \pm 2 mJy .
We estimate a systematic uncertainty in the power law index \delta p \lesssim 0.15 , where the largest error comes from the assumed form of the dust temperature falloff with radius .
This determination of the inner density structure of B335 has a precision unique amongst protostellar cores , and it is consistent with the r ^ { -1.5 } profile of gravitational free-fall , in accord with basic expectations for the formation of a star .
The flux ( and implied mass ) of the compact component in B335 is typical of the disks around T Tauri stars .