Gravitationality stable Bok globule

A molecular and optical study of an isolated, low-mass (approx.10 M/sub sun/ ) Bok globule is presented. Analysis of the cloud's surface brightness reveals the object to be centrally condensed. Molecular emission lines are unusually narrow, implying that any turbulent motions within the cloud are subsonic. Consequently, thermal pressure dominates dynamical support by a wide margin within the globule. A stability assessment based upon the cloud properties obtained from the observations suggests that the cloud is close to a state of hydrostatic equilibrium. Owing to the relatively insignificant role played by turbulent pressure in supporting the globule, stable cloud configurations can be modeled with some confidence. A pressure-bounded, centrally condensed model with kinetic temperature increasing outward yields good agreement with the observed cloud radius and central visual extinction, as well as with the mass inferred from the observations. Neither the requirement of equilibrium nor the slight ellipticity of the cloud appears to demand ad hoc postulation of a significant internal magnetic field. The hydrostatic models are also used to construct microturbulent CO line formation models of the globule; these agree well with the observations