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1. Introduction

  Bars are common features of disc galaxies, happening in more than one third of all disk galaxies. Theoretical works on barred spirals have been successful so far in explaining several observed features: gas velocity fields and observed shapes of the bar, for instance, have been reproduced with a satisfying agreement with the observations. Observational studies of the motion of the ionized gas and of the HI are available in the literature since dozen of years (see Sellwood & Wilkinson 1993 for a review on observations and theories).

Concerning the stellar motions, the situation for barred galaxies is quite different. Stellar orbits across and near the bar have been accurately modeled but, in spite of these progresses in the theory, few new data on the stellar velocity fields in barred spirals are available in the literature. Our knowledge of SB0, where emission lines or 21 cm flux are generally fainter than in spirals, is based on few, well studied objects, such as NGC 936 (Kormendy 1983) and NGC 4596 (Kent 1990). However, many of the published data concern peculiar cases, and studies of single, normal SB0s are very rare to be found in the literature. On the other side, SB0s would be ideal systems to study the structure of the bars and the stellar orbits, being more free than spiral galaxies by the presence of gas and dust.

Figure 1: Images of the studied galaxies, from Digitized Sky Survey. The field for each galaxy is tex2html_wrap_inline1366 tex2html_wrap_inline1368 tex2html_wrap_inline1370

Table 1: Log of the observations

Only quite recently, some attempts to observe the stellar kinematics of a large sample of early-type barred systems has been performed (Kormendy 1982b; Bettoni & Galletta 1988; Jarvis et al. 1988). In these papers, the most important questions concern the dynamical interaction of the bars with the bulges and/or the halos and the three-dimensional structure of bars and ovals. The results of these studies show that stellar orbits also are influenced by the bar, with streaming motions deviating from circular orbits (Kormendy 1982a,b; Kent 1990) and with orbits sometimes retrograde (Bettoni 1989).

In order to better understand the dynamical structures present in these barred systems, we felt the need to have a set of data obtained with similar quality (velocity resolution, sky brightness, reduction methods) and for a number of barred S0s as wide as possible. As described below, the data presented here have all a velocity dispersion better than 45 km stex2html_wrap_inline1572 and are taken for each galaxy at least at four different position angles on the sky, to study the velocity field of the single galaxies. We also have the goal of providing homogeneous and detailed new data for the future models of barred galaxies.

In this paper we present new velocity and velocity curves for six galaxies (five SB0 and one SBa, NGC 3271, NGC 4371, NGC 4596, NGC 4754, NGC 6744 and NGC 7079), and we analyze the original data for 8 additional cases, observed with similar instruments, but discussed in previous studies. In Sect. 2 we give an overview of the observations; in Sect. 3 we describe the observed characteristics of each galaxy and finally in Sect. 3 (click here) the main results of this study.

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