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

Abstract. 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 with the 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_☉, diameters between 1.2 and 5.7 × 10⁴ AU (0.06 and 0.28 pc), and mean densities of about 10⁴ cm^-3, all in good 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 decrease in 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 similar to the stars in Taurus, suggesting that the spatial distribution of stars evolves directly from the primordial spatial distribution of high-density material.

Dust extinction map of the Barnard 59 region at a spatial resolution of 20''. The white solid line contours mark levels of visual extinction at A_V = 5, 7, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, and 90 mag.