The line observations indicate that mostly originates from the envelope and the limb-brightened edges of the outflow, whereas the emission is more directly associated with the compact continuum source. Weak evidence for rotation has been found. Comparison of the two line tracers shows proeminent redshifted self-absorption in the spectrum which is very suggestive of infall motions. The infalling medium seems to be confined in a large (a few thousands AU) flattened structure.
These observations provide a quite detailed description of the structure of a Class 0 protostar, which appears to have a complex vicinity where the outflowing and accreting phenomena are closely linked together (Fig. 4)
Figure: 2.5'' observations of the protostar L 1157-mm: (Left) J=1-0 (thick histogram), J=1-0 (filled) and J=1-0 interferometric + single-dish (thin) spectra observed towards the central position. (Right) mm continuum emission (greyscale) surimposed with the integrated CO emission: the extended component of the continuum emission is associated with the edges of the molecular outflow. The white ellipse is the formal result of a fit of the compact central source.