HIGH-RESOLUTION OBSERVATIONS, KINEMATICS, AND DYNAMICS OF THE BARRED SPIRAL NGC 1073

High spatial resolution (20″) neutral hydrogen observations of the barred spiral galaxy NGC 1073 are used to map the kinematics and gas density with a velocity resolution of ∼12 km s-1. The kinematics indicate that the galaxy is seen nearly face-on, i.e., inclination ∼18°. The rotation curve rises steeply in the inner part, flattening at a maximum circular velocity of 106 km s-1. The steeply rising part is approximately the region occupied by the bar. The rotation curve begins to decrease at r = 2′.5. This behavior may be the kinematic signature of a truncated disk. This feature appears at approximately the edge of the optical disk. Other notable features in the H I are the lack of spiral features, the presence of a gas bar, and the very good circular symmetry. The appearance is that of a nearly circular gaseous disk with an almost complete ring surrounding a central depression, with a bar. Dynamical models that reproduce the H I observations are constrained by the large-scale structure and kinematics of the gas and by the near-infrared morphology of the bar. The dynamical components considered are (1) an axisymmetric n = 0 Toomre disk, (2) a triaxial stellar bar, and (3) an oval distortion of the axisymmetric disk. The disk and the bar (∼7% of the disk mass) are sufficient to reproduce the broad ring and gas bar seen in the neutral hydrogen, with the weak oval distortion providing perturbations in the radial velocity field. No halos are added to the dynamical models reported here, but halo models which match the truncation feature indicate that the halo and disk masses within the disk radius must be comparable.