spectroscopy of double - barred galaxies

The first results of the observational program of the study of 2D-kinematics in double-barred galaxies are presented. We show that, for the main part of the sample, the inner bars do not affect the circumnu-clear stellar kinematics. Therefore, they are not dynamically decoupled structures. Various types of non-circular gas motion were found in many galaxies. The analysis of the ground-based and HST optical and NIR images reveals mini-spirals in about half of the investigated objects. We suggest that so called " double-barred galaxies " are, in fact, galaxies with very different circumnuclear structure. 1. Double-barred galaxies: history of the problem. Quarter of century ago, de Vaucouleurs (1975) found that an inner bar-like structure was nested in a large-scale bar at the optical image of NGC 1291. The first systematic observational study of this phenomenon was made by Buta & Crocker (1993) who published a list of 13 galaxies, in which the secondary bar was arbitrarily oriented in relation to the primary one. In the following years the isophotal analysis technique had allowed to detect secondary bars at the optical Also numerous theoretical papers exist, but secondary bar dynamics is still far from being understood. Shlosman, Frank & Begeman (1989) have shown that a new circumnuclear bar may be formed as a result of gas instabilities within a primary bar. Maciejewski & Sparke (2000) found some families of closed orbital loops which can support both bars. Dynamics of stellar-gaseous secondary bars have been studied in numerical simulations To test these theoretical predictions, new observational data is required. In this paper we try to find an answer to the question – Are the secondary bars dynamically decoupled systems?