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Dynamics of embedded bars and the connection with AGN. I. ISAAC/VLT stellar kinematics
We present new stellar kinematical profiles of four galaxy hosts ofactive galactic nuclei, using the 12CO bandhead around 2.3 mum with the ISAAC/VLT spectrograph. We find that the nuclear bars ordiscs, embedded in large-scale primary bars, have all a decoupledkinematics, in the sense that the maximum of the rotational velocityoccurs in the nuclear region. In three cases (NGC 1097, NGC 1808 and NGC5728), the velocity dispersion displays a significant drop at thenucleus, a rarely observed phenomenon. We also detect kinematicalasymmetries (m=1 mode) along the nuclear bar major-axis of NGC 1808 andNGC 5728, dynamical counterparts of corresponding asymmetries in thesurface brightness. We have derived simple dynamical models in anattempt to fit the kinematics of each galaxy and reconstruct the fullvelocity field. For all four targets, the fits are good, and confirm thepresence of the decoupled nuclear components. These models cannothowever reproduce the observed central drop in the dispersion. Wesuggest that this drop is due to a transient cold nuclear disc, fuelledby gas inflow along the bar, that has recently formed new stars. Basedon observations collected at the VLT telescope of European SouthernObservatory, Paranal, Chile, ESO Nos. 64.A-0076, 65.A-0031).
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
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