THE SMOOTHNESS OF CO LINE-PROFILES IN ORION - IMPLICATIONS FOR CLUMPINESS

We have obtained spectra with very high signal-to-noise ratio and spectral resolution of the (CO)-C12 and (CO)-C-13 J = 1 --> 0 transitions toward several positions in the Orion region. These observations test the extent to which the clumpy structure of this region is reflected in the velocity structure of the spectra. The smoothness of the profiles is such that if the cloud is assumed to have a constant clump volume filling factor, an unrealistically large number of clumps is necessary to reproduce the observations. A volume filling factor which increases from a small value at the surface to a large value at the core may be more appropriate for this source.