Deep Near-infrared Survey of the Pipe Nebula. II. Data, Methods, and Dust Extinction Maps

We present a new set of high-resolution dust extinction maps of the nearby and essentially starless Pipe Nebula molecular cloud. The maps were constructed from a concerted deep near-infrared imaging survey withthe ESO-VLT, ESO-NTT, CAHA 3.5 m telescopes, and 2MASS data. The new maps have a resolution three times higher than the previous extinction map of this cloud by Lombardi et al. and are able to resolve structures down to 2600 AU. We detect 244 significant extinction peaks across the cloud. These peaks have masses between 0.1 and 18.4 M sun,diameters between 1.2 and 5.7 × 104 AU (0.06 and 0.28pc), and mean densities of about 104 cm-3, all ingood agreement with previous results. From the analysis of the mean surface density of companions we find a well-defined scale near 1.4× 104 AU below which we detect a significant decreasein structure of the cloud. This scale is smaller than the Jeans length calculated from the mean density of the peaks. The surface density of peaks is not uniform but instead it displays clustering. Extinction peaks in the Pipe Nebula appear to have a spatial distribution similarto the stars in Taurus, suggesting that the spatial distribution of stars evolves directly from the primordial spatial distribution of high-density material.