Herschel column density map of the B59 and Stem in the Pipe complex, as presented in Fig. 1. The red segments provide the direction of the local magnetic field as measured from near-infrared dust polarization data (Franco et al. 2010). The blue segments mark a  ± 2σ deviation on either side of the nominal field direction. Note that gravitationally unstable regions, those lying above N_H2 ≃ 7 × 10²¹ cm^-2, correspond to the white areas.

Blow-ups of Fig. 1 showing the column density images of a portion of the Stem (left) and the B59 (right) regions over which the filament networks as traced by the DisPerSE algorithm are plotted. On these images, we can see better the “grid-like” pattern in the Stem, and the converging pattern of B59. The direction and length of each arrow show the direction and amplitude, respectively, of the asymmetry in the corresponding column density profile, for filaments having  −60° < PA <  +30° and asymmetry uncertainty better than 10%.

Histograms of position angles for all the filaments identified with DisPerSE (solid black line) and the selected filaments (purple). A Kolmogorov-Smirnov test indicates a  ~87% chance that these two sets of filaments have the same parent distribution of position angles.

Histogram of the deconvolved FWHM widths (black solid line) of the filaments identified in the Herschel Pipe images presented in this paper. The histogram peaks at  ~0.08 pc and has a standard deviation of 0.02 pc. The blue dashed line represents the histogram of Jeans lengths measured from the central column densities of the filament (see Arzoumanian et al. 2011).

Schematic view of the Pipe nebula cloud, Ophiuchus streamers and Sco OB2 association. The solid straight lines represent the streamers and main body of the Ophiuchus and Pipe molecular clouds, respectively. The plus symbol marks the central position of the Sco OB 2 association. The star symbols represent the positions of some of the main members of the association, and the HI bubble observed by de Geus (1992) is also indicated.