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A. Alonso-Herrero (Steward Observatory), R. Maiolino (Osservatorio Astrofisico di Arcetri), A. C. Quillen, M.J. Rieke, G.H. Rieke (Steward Observatory)
The mechanism responsible for transporting gas from the 100\,pc scale into the innermost regions of an active galactic nucleus (AGN), to fuel it and obscure it, is still unclear. One possibility is that a 100\,pc-scale gaseous disk becomes dynamically unstable and forms a gaseous bar which in turn transports material into the nuclear regions. We present HST/NICMOS images of the nuclear region of the Seyfert 2 galaxy Circinus. The NICMOS H-K color map (which traces the extinction) shows evidence for a ~100 \,pc-diameter gaseous-dusty bar, although only one side of the bar is seen. The HST/NICMOS images are complemented with integral field spectroscopy of the molecular hydrogen line H2(1,0)S(1) at 2.12\,\mum. The latter data are used to map the velocity field of the molecular gas. Our results are in agreement with the kinematics expected for gas in a barred potential. In particular, strong inflow motions are apparent on the leading side of the bar. We will also discuss the relation between the gas bar and the morphology of the emission lines Pa\alpha (1.87\,\mum), [Si\,{\sc vi}]1.962\,\mum, H2(1,0)S(1) at 2.12\,\mum and [Fe\,{\sc ii}]1.644\,\mum NICMOS images.