The Structure and Dynamics of Filamentary Molecular Clouds

Abstract

We summarize models of self-gravitating, filamentary molecular clouds that are threaded by helical magnetic fields. We review the observational evidence suggesting that some clouds may exist in this regime. An analytic limit is derived that demonstrates why the Fiege & Pudritz model always tends to an similar to r (-(1.9 +/- 01)) density profile at large radius, in agreement with observations. An equation is also derived for the radial compression or expansion of filamentary clouds that are out of equilibrium. We use this analysis to show that filamentary clouds are extremely stable with respect to radial collapse or expansion, which allows them to survive long enough to fragment gravitationally along their axes. Fragmenting, helically magnetized filaments have a unique kinematic signature, which is discussed and compared with recent observations. We discuss models of prolate cores that form within filaments. Polarimetry models of filaments are discussed and compared with the data.