1996A&A...312..585L

A complete and unbiased survey of 237 dust globules from the catalog of Clemens & Barvainis (1988) has been made in the (1,1) and (2,2) inversion lines of ammonia. Whereas NH₃(1,1) emission is found in 74 sources, the NH₃(2,2) line is detected only in 17 sources. Complete ammonia maps of 15 globules show angular sizes of between 45" and 85". The FWHP angular sizes of these clouds based on the C¹⁸O(1-0) emission are between 2 and 9 arcminutes. Accurate determinations of the kinetic temperatures show that the temperatures of all the globules in the study are between 8.5 and 11.5K. From NH₃ excitation temperatures of between 4.5 to 8K we determine H₂ densities with typical values around (2-4).10⁴cm^–3. Presumably, the more extended C¹⁸O emission arises from lower density gas. The masses of the mapped globules range up to 100 solar masses with typical values between 2 and 45 solar masses. Considerations of stability from a comparison of turbulent, thermal and gravitational energies show that all the globules are close to equilibrium.