FORMALDEHYDE ABSORPTION IN THE NUCLEUS OF NGC-3628

NGC 3628 displays strong absorption against the extended nuclear radio source. Results from a VLA study of the nuclear H2CO absorption and Arecibo H I data are reported here and are integrated with those from earlier H I and OH emission and absorption studies. The nuclear absorption originates in two components: a rapidly rotating molecular disk and an anomalous structure with a distinctly different velocity gradient and central velocity. The anomalous structure is interpreted in terms of the perturbed density and velocity field, resulting from a recent interaction with NGC 3627, another member of the Leo Triplet.