Appendix A: Comparison with literature

Figure A.1: The ionized gas velocities derived in this study for NGC 2683, NGC 3200, NGC 4419 and NGC 7331 compared with those obtained by other authors: ASZ89 = Afanasiev et al. (1989); B99 = Bottema (1999); BC75 = Barbon & Capaccioli (1975); MFB92 = Mathewson et al. (1992); R+82 = Rubin et al. (1982); R+85 = Rubin et al. (1985); RWK99 = Rubin et al. (1999); $\rm S+95 = Sperandio$ et al. (1995).

Figure A.2: The stellar velocities and velocity dispersions derived in this study for NGC 224, NGC 470, NGC 2841, NGC 3031, NGC 3368, NGC 3810, NGC 5854 and NGC 7331 compared with those obtained by other authors: B99 = Bottema (1999); $\rm B+93 = Bower$ et al. (1993); BSG94 = Bender et al. (1994); DR88 = Dressler & Richstone (1988); FBD86 = Fillmore et al. (1986); H+99 = Héraudeau et al. (1999); H+00 = Haynes et al. (2000); HS98 = Héraudeau & Simien (1998); K88 = Kormendy (1988); $\rm P+96 = Prada$ et al. (1996); SP97 = Simien & Prugniel (1997); SVB86 = Sil'Chenko et al. (1997); WRF84 = Whitmore et al. (1984).

Figure A.2: continued.

In this section we perform a comparison between the gaseous and stellar kinematical data we obtained for the sample galaxies with the velocity curves and velocity dispersion profiles available in the literature in order to assess the accuracy and reliability of our measurements. In most cases, differences between different authors are due to slit centering and positioning and to the different analysis techniques, or both (see Fisher 1997 for a discussion).

As far as our sample galaxies are concerned, ionized gas velocity curves have been already measured along the major axis of NGC 2683, NGC 3200, NGC 3898, NGC 4419, and NGC 7331. Apart from NGC 3898 presented in Pignatelli et al. (2001) the other cases are discussed here briefly and shown in Fig. 1.

NGC 2683: The complex kinematics of this galaxy has been unveiled by Pompei & Terndrup (1999) who isolated two kinematically distinct gaseous components giving rise to a "figure-of-eight'' velocity curve. The fast and the slow-rotating components are unresolved in our spectrum as well as in that of Barbon & Capaccioli (1975). We therefore measured intermediate $V_{\rm g}$'s and higher $\sigma _{\rm g}$'s.

NGC 3200: The agreement between our $V_{\rm g}$ and that measured by Rubin et al. (1982) is excellent. This is also true for Mathewson et al. (1992) in the outer regions. The shallower central gradient can be explained taking into account for their lower spatial resolution.

NGC 4419: Our data closely matches those obtained by previous authors. This is not the case for only of the $V_{\rm g}$ rotation curves given by Sperandio et al. (1995). In this case their lower spatial resolution produces the observed shallower central gradient but it can not account for the strong discrepancy we see at large radii on both sides.

NGC 7331: Our $V_{\rm g}$'s matches those by Bottema (1999). A difference in the heliocentric systemic velocity and the different position angle of the slit ( ${\rm PA}=170^\circ$) may explain the shift the $V_{\rm g}$ curve by Afanas'ev et al. (1989).

Major-axis stellar kinematics have been previously published for NGC 224, NGC 470, NGC 772, NGC 2683, NGC 2841, NGC 3031, NGC 3368, NGC 3810, NGC 3898, NGC 5854 and NGC 7331. They are compared with our data in Fig. A.2 except for the cases of NGC 772 and NGC 3898 which we analyzed in Pignatelli et al. (2001).

NGC 224: The discrepancy observed along the NE axis between our data and those by Kormendy (1988) and by Dressler and Richstone (1988) may be the result of an incorrect sky subtraction in our data. An overestimation of the sky level due to the large size of the galaxy covering all the slit area may produce the higher σ_* and shift in $V_\star$ we actually measure.

NGC 470: The $V_\star$'s we measured are consistent with those of Héraudeau et al. (1999) while less satisfactory is the comparison between our and their σ_*. In particular their values range between about 70 and 170  $\rm km\;s^{-1}$, whereas we measured σ_*   $\rm km\;s^{-1}$ at almost all radii (probably due to a template mismatching effect).

NGC 2683: We do not resolve the counter-rotating stellar components observed by Pompei & Terndrup (1999) because we have no enough spectral resolution and either a good S/N in our spectra.

NGC 2841: In the centre the $V_\star$ value we obtained is within the scatter of the other data sets, the same is true for σ_*. however further out from the nucleus our $V_\star$ and σ_* are are somewhat lower than those found in literature.

NGC 3031: We measure the same $V_\star$ gradient as Bender et al. (1994) and Héraudeau & Simien (1998) in the inner . Further out our $V_\star$ continues to increase. The differences between the three $V_\star$ sets are as large as 50-80  $\rm km\;s^{-1}$. In the same radial region our σ_* agrees with the velocity dispersions by Bender et al. (1994) but are about 50  $\rm km\;s^{-1}$ lower than those by Héraudeau & Simien (1998). σ_* measurements do coincide in the centre. These differences in $V_\star$ and σ_* are due to the different instrumental setup used for the different observations. We used a very spatial resolution, so the velocity gradient we measure is more accurate than that of the other authors. The differences in the values of σ_* between our measurements and those obtained by Héraudeau & Simien (1998) are probably due to a template mismatching effect.

NGC 3368, NGC 3810 and NGC 5854: Our major-axis kinematics are in good agreement with the literature. This is also true for the $V_\star$ we measured along the minor axis of NGC 5854.

NGC 7331: The $V_\star$ gradient measured by Héraudeau & Simien (1998) is shallower than that by us and other authors. We suggest it may be due to a different position of the slit. Our σ_* radial profile shows a faster decrease and at larger radii it is marginally consistent with that by Bower et al. (1993).

For some of the sample galaxies velocity fields for the cool gaseous component have been obtained using CO molecular lines and/or H  I 21-cm line and can be compared to our ionized-gas velocity curves to have some insights into the inner-to-outer gas distribution and motion.

  

Table A.1: Kinematic properties of the sample galaxies

$$\tiny { \begin{tabular}{lrrcrrcccccccrrcll} \hline \multico... ...266\pm 10$ & $194\pm 33$ && 0.6 & 0.6\\ \hline \end{tabular}}$$

Notes - Columns (2-3): central velocity dispersion of ionized gas and stars. Columns (4-5): velocity dispersion of ionized gas and stars at $R_{\rm e}/4$. Columns (6-7): central velocity gradient of ionized gas and stars. Columns (8-9): velocity gradient of ionized gas and stars at $R_{\rm e}/4$. Columns (10-11): ionized-gas and stellar rotation velocity at $R_{\rm e}/4$ obtained from the observed velocity corrected for systemic velocity and inclination given in Table 1. Columns (12-13): Extent of the ionized-gas and stellar kinematic radial profiles obtained in this paper in units of R₂₅.

NGC 2541: The H  I data by Broeils & van Woerden (1994) show a symmetric outer rotation curve with no particular peculiarities.

NGC 2683: The H  I position-velocity diagram by Broeils & van Woerden (1994) shows two kinematically distinct components giving a "figure-of-eight'' appearance to the diagram. These components may be associated with the fast and slow-rotating components observed by Pompei & Terndrup (1998) both in the stellar and ionized-gas velocity curves. Figure-of-eight velocity curves have been explained by Kuijken & Merrifield (1995) to be due to the presence of a bar (see other examples in Vega Beltrán et al. 1997; Bureau & Freeman 1999).

NGC 2841: Sofue et al. (1999) obtained an extended and well-sampled inner-to-outer rotation curve by combining H$\alpha$, CO and H  I observations. Rotation attains a sharp maximum near the centre and flattens outwards and asymmetries seem to be confined in the radial region we observed.

NGC 3031: Sofue (1997) combined different optical and radio data sets to trace gas rotation of this spiral galaxy out to more than 20'. There is no evidence of kinematical decoupling between gas and stars even if our higher-resolution data show that in the inner $\pm1'$the gas velocity curve is highly disturbed and less regular than the stellar one.

NGC 3368: The H  I and CO velocity fields have been derived by Schneider (1989) and Sakamoto et al. (1999) respectively. The large fraction of H  I is distributed outside the optical disk indicating the possible capture of intergalactic gas. On the contrary CO is concentrated towards the inner regions and its asymmetric position-velocity diagram matches our [O  III] $\,\lambda5006.8$ velocity curve. Gas infall due to the galaxy bar and interactions has been considered by Sakamoto et al. (1999) to explain CO distribution.

NGC 3898: The H  I distribution and velocity field have been studied in detail by van Driel & van Woerden (1994). The comparison of these data with our ionized-gas kinematics and the H$\alpha$-imaging by Pignatelli et al. (2001) suggests that both ionized and neutral hydrogen have a regular velocity field and a smooth distribution.

NGC 7331: Sofue (1997) obtained a rotation curve for the gaseous component from CO and H  I lines. The global rotation appears normal with no peculiar behaviour. There is no gas component associated to the counter-rotating bulge claimed by Prada et al. (1996).