Helical fields and filamentary molecular clouds — II. Axisymmetric stability and fragmentation

In Paper I (this issue), we constructed models of filamentary molecular clouds that are truncated by a realistic external pressure and contain a rather general helical magnetic field. We address the stability of our models to gravitational fragmentation and axisymmetric magnetohydrodynamically driven instabilities. By calculating the dominant modes of axisymmetric instability, we determine the dominant length-scales and growth rates for …