Manifestations of electric currents in interstellar molecular clouds
Attention is drawn to filamentary structures in molecular clouds and the existence of subfilaments of sinusoidal shape and also of helix-like structures is pointed out. For two dark clouds, the Lynds 204 complex and the Sandqvist 187-188 complex (the Norma 'sword'), a detailed study of such shapes is made, and the possible existence of helices wound around the main filaments is found. All these features suggest the existence of electric currents and magnetic fields in these clouds. On the basis of a generalization of the Bennett pinch model, the magnitudes of the currents expected to flow in the filaments are derived. Values of column densities, magnetic field strengths, and directions of the fields are derived from observations. Magnetic fields with both toroidal and axial components are considered. This study shows that axial currents on the order of a few times 10 13 A are necessary for the clouds to be in equilibrium.