NGC 7479: A Case Study

Abstract

The most salient features of the barred spiral galaxy NGC 7479 include the unusually strong and long bar, asymmetric spiral structure and peculiar dust lanes. The central, bar-dominated region has been robbed of neutral atomic gas. The neutral hydrogen kinematics of the strong western spiral arm are consistent with substantial non-circular motions. In contrast, the molecular gas is strongly concentrated in the nucleus and along the bar dust lanes. A molecular disc with near-circular motion is found in the nuclear area. Outside this component, the molecular gas has a strong radial velocity component consistent with inflow. The velocity gradients across the bar dust lanes show jumps of a few hundred km s-1. A comparison of the dust/gas lane morphology between the observations and numerical simulations suggests that the corotation radius is at 1.1 times the bar length. I have modelled many of the peculiar morphological and kinematic features in numerical simulations of a minor merger. The predicted position of the merging companion matches the position of a bright clump in the bar with perturbed kinematics.