Interstellar neutral hydrogen filaments at high galactic latitudes and the bennett pinch

Abstract

Observed properties of interstellar neutral hydrogen filaments suggest the presence of the Bennett pinch as described by the Carlqvist relationship with rotation around the filament axes included. A brief summary is first given of three ways in which a filament model for interstellar “cloud” structure was tested. Preliminary results from highresolution HI mapping of gas and dust in an apparent HI “cloud” indicate that the neutral gas and dust within and around its boundary is itself highly filamentary. An attempt to detect magnetic fields in this and similar features using the Zeeman effect technique at the 21-cm wavelength of interstellar neutral hydrogen set upper limits of a fewµG. In contrast, the strength of the toroidal magnetic field expected from the examination of the Carlqvist relationship is of order 5µG, which would be produced by a current of 1.4 · 10¹³ A. Zeeman effect technology is at present not able to detect toroidal magnetic fields of this order at the edge of barely resolved HI filaments. Nevertheless, currently available high-resolution HI data suggest that interstellar filament physics should take into account the role of currents and pinches for creating and stabilizing the structures.