Isophote twists in the nuclear regions of barred spiral galaxies

We present near-IR (1.2-2.2 μm) surface photometry within the central regions of the intermediate-late type barred spiral galaxies NGC1097, NGC4736 and NGC5728. The observed isophotes show striking (60°-90°) isophote twists with respect to the position angles of the principal bar/lens components. In NGC 1097 and NGC5728 such twists are immediately interior to circumnuclear rings evident in both our, and in previously published, data. Several possible mechanisms for the formation of such structures within barred potentials are considered. It is argued that the lack of evidence for active star formation within those regions dominated by the isophotal twists implies that they are not due to the presence of M supergiants formed within inner gas flows