Following the work of Binney et al. (1991) on the interpretation of our Galaxy's CO l-v diagram, we have developed a model on the gas kinematics of the inner regions of NGC891 that explains satisfactorily the major features of the CO p-v diagram. In our model, the flow of molecular gas is driven by a bar that has corotation at r3 kpc and that is viewed at an angle 45 from its major axis. Molecular clouds circulate along x orbits (elliptical orbits perpendicular to the bar) between the two Inner Linblad Resonances (ILR), and partly populate x orbits (ellipses parallel to the bar) in the outer regions (from the outer ILR up to the corotation circle). We can also explain the radial distribution of molecular gas: the great ring of molecular material at r4.5--6 kpc might be associated with the Outer Linblad Resonance of the bar (OLR) and the adjacent hole of molecular gas inside this radius, with the corotation circle.
The observed kinematics of molecular
gas in the center of the edge-on spiral NGC5907, as well as
a number of other galaxies, could be also interpreted in terms of
highly elliptical orbits driven by bars or triaxial potentials.