High-resolution, wide-field imaging of the HL Tauri environment in (CO)-C-13 (1-0)

We present a high-resolution image of the region near HL Tau in (CO)-C-13 ( 1-0) over a region of 3' made with the BIMA array, supplemented by data fro m the NRAO 12 m telescope to include emission structures with low spatial f requencies. We find evidence for a shell of dimensions similar to 2' x 1.'5 (similar to 0.08 x 0.06 pc), with XZ Tau being the closest known source to its center. The (CO)-C-13 map is consistent with an expanding bubble that has blown out on the far side from earth. Portions of the bubble wall are s een in optical scattered light. HL Tau is situated in the bubble wall; the evacuated region corresponds to the truncation in the reflection nebula nor theast of HL Tau. Although it is thought that a remnant protostellar envelo pe is still infalling onto HL Tau, the existence of the expanding bubble ma kes it difficult to interpret the geometry and kinematics of the HL Tau cir cumstellar material. Our results demonstrate the importance of including lo w-spatial frequency emission for the interpretation of interferometer maps.