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 r
4.5--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.