The equilibrium state of molecular regions in the outer Galaxy

A summary of global properties and an evaluation of the equilibrium state o f molecular regions in the outer Galaxy are presented from the decompositio n of the FCRAO Outer Galaxy Survey and targeted (CO)-C-12 and (CO)-C-13 obs ervations of four giant molecular cloud complexes. The ensemble of identifi ed objects includes both small, isolated clouds and clumps within larger cl oud complexes. The (CO)-C-12 luminosity function and size distribution of a subsample of objects wit well-defined distances are determined such that D eltaN/DeltaL(CO) = (3 x 10(4))L-CO(-1.80+/-0.03) and DeltaN/DeltaR(e) = (1. 7 x 10(4))r(e)(-3.2+/-0.1). (CO)-C-12 velocity dispersion show little varia tion with cloud sizes for radii less than 10 pc. It is demonstrated that th e internal motions of regions with M-CO = X-CO L-CO > 10(4) M-. are bound b y self-gravity, yet the constituent clumps of cloud complexes and isolated molecular clouds wit M-CO <10(3) M-. are not in self-gravitational equilibr ium. The required external pressures to maintain the equilibrium of this po pulation are (1-2) x 10(4) cm(-3) K.