Magnetic field structure in Serpens South

We made near-infrared polarimetric observations toward Serpens South. This region contains three dense filaments that are roughly parallel to one another. Using the histogram of relative orientations, the three filaments are found to be roughly perpendicular to the global magnetic field. The morphology of the plane-of-sky (POS) magnetic field and molecular gas suggests that the magnetic field plays an important role in the filament formation and evolution. Applying the Davis-Chandrasekhar-Fermi method, the POS magnetic field strengths are estimated to be 10-80 μG. The evaluated mass-to-flux ratios indicate that the center filament is magnetically supercritical, while the others are approximately magnetically critical. We speculate that the filaments are formed by fragmentation of a sheet-like cloud that was created through the gravitational contraction of a magnetized, turbulent cloud.