4. The galaxies

ESO 316-G029: Despite the asymmetric ring-like structure in the nuclear region of this galaxy (see Fig. 1 (click here)a) we classified it as a normal galaxy. It is a barred spiral with two well developed arms. The arms are relatively faint and it is noted that there is a knot at the end of the NE arm. The color of this clump, , is indicative that it was probably caused by the disruption of the arm itself.

The luminosity profiles shown in Fig. 2 (click here)a, exhibit a very uniform behaviour. The feature at r = 15'' is probably due to the presence of the inner ring which is more conspicuous in the B band.

We measured the rotation curve of this galaxy up to a radius of 4 kpc. It is seen in Fig. 3 (click here)a that the semi-amplitude, corrected for the galaxy inclination (b/a = 0.4), is  km ^-1.

This galaxy has a LINER-type nucleus as it can be seeing from its spectrum shown in Fig. 4 (click here)a. Although the observed [NII]/H ratio barely satisfies the definition of a LINER galaxy (Sekinguchi & Wolstencroft 1992, hereafter S&W), the spectrum shows relatively strong [OIII] 4959, 5007 Å emission lines. Moreover, the EW(H + [NII]) = 22 Å measured from the nuclear spectrum is high when compared to a typical galaxy spectra (Kennicutt 1992). The calculated line flux ratios from the pure-emission spectrum of this galaxy are listed in Table 8 (click here). From these data it was derived an internal reddening E(B-V) = 1.25, the higher value in the whole sample.

   

Galaxy E(B-V)

ESO 316-G029 1.25 4.04 2.95 0.08 0.72 0.23

NGC 3250E 0.18 0.98 0.70 0.02 0.19 0.31

ESO 317-G041 0.59 0.59 1.94 0.05 0.56 0.38

ESO 266-G015 0.25 0.54 0.17 0.03 0.26 0.25

AM 2054-433N 0.11 1.38 2.44 - 3.53 1.45

AM 2054-433S 0.40 1.55 5.30 0.25 1.64 0.81

NGC 3250 E: Although the structure of this galaxy is rather peculiar (see Fig. 1 (click here)b), we find no evidences of a merger. The B image shows a very irregular and bright main body wrapped up by three spiral arms. The nucleus is not in the galaxy center and it can be also noticed a conspicuous bar.

The B-V color map of this galaxy shows several very blue knots distributed along the arms. These regions have (B-V) values ranging from 0.1 to 0.4 indicating ongoing star formation. Particularly interesting is the compact region located at the end of the southern arm for which we obtain (B-V)=0.2.

As it can be seen in Fig. 2 (click here)b the luminosity profiles of this galaxy show an interesting property. Two exponential behaviours for r < 15'' and for r > 15'', suggests that the galaxy has two different discs with scale lengths  kpc and  kpc respectively.

According to the criteria given by Kennicutt (1992), the whole-aperture spectrum of this galaxy corresponds to a starburst galaxy as it can be seen in Fig. 4 (click here)b. From the nuclear spectrum we obtain EW(H + [NII]) = 60 Å, which is about 3 times higher than the corresponding average for Sb/Sc galaxies (Liu & Kennicutt 1995, hereafter L&K). On the other hand, the whole-aperture and nuclear spectra give similar EW(H + [NII]) values indicating that the galaxy is probably under a global starburst (see Table 7 (click here)). According to the models of L&H the age of the burst is around 10 Myr.

ESO 317-G041: This is clearly another peculiar galaxy whose elongated main body shows several filaments or tails which are not aligned with major axis (see Fig. 1 (click here)c).

Due to bad tracking (see the bright star located at the E in Fig. 1 (click here)c) and calibration problems we could not obtain the luminosity profiles of this galaxy.

The integrated spectrum of this object corresponds to a starburst galaxy (see Fig. 4 (click here)c). However, the absorption spectrum is more conspicuous than the spectrum of the ESO . This fact is particularly evident in the blue, where the Balmer spectrum of early-type young stars have become the dominant spectral feature.

From the nuclear spectrum we obtain EW(H + [NII]) = 58 Å, while for the integrated spectrum EW(H Å. These values date the age of the starburst event about 10 Myr.

We measured the rotation curve of this galaxy up to a radius of 7 kpc. The maximum rotational velocity is  km s^-1 and it is reached at r = 4 kpc (see Fig. 3 (click here)b).

NGC 3318: This is a very peculiar galaxy. The blue image shows a very bright stellar-nucleus located in the middle of a bar that lies along the direction (see Fig. 1 (click here)d). From this bar two well developed and asymmetrical arms emerge. They are very bright, specially the southern one, and they show very blue colors, , indicating ongoing star formation. Another interesting feature of this galaxy is a ring-like structure that emerges from the extreme of the southern arm and seems to be in a different plane than the disk.

The luminosity profiles shown in Fig. 2 (click here)c exhibit many features that are signatures of the rather complicated structure of this galaxy. From the B-V map it can be noticed several knots distributed throughout the galaxy with rather blue colors, .

Despite the peculiar morphology of this galaxy the integrated spectrum corresponds to a Sb galaxy (see Fig. 4 (click here)d). We measure EW(H + [NII]) = 26 Å, which is typical for this type of galaxies. However, the nuclear and integrated spectra of this galaxy are slightly different. The integrated spectrum shows a stronger [OII] 3727 Å\ emission line and lower [NII]/H ratio than the nuclear spectrum due to the presence of HII regions outside the nucleus.

Figure 3 (click here)c shows the rotation curve up to a radius of 7 kpc where a high value of the maximum velocity,  km s^-1 is reached at r = 4 kpc.

NGC 3378: By inspection to Fig.1 (click here)e we classify this galaxy as a normal spiral. It shows a faint stellar-nucleus and a bright disk from which three spiral arms emerge. In the B-V map we observe several blue knots distributed throughout the arms. The (B-V) values range from 0.3 to 0.4 indicating ongoing star formation.

The luminosity profiles shown in Fig. 2 (click here)d exhibit an exponential behaviour in the whole galaxy. The presence of a feature at r = 30'' is due to the contribution of the spiral arms. From the decomposition profiles we measured for this galaxy  Kpc.

The whole-aperture spectrum corresponds to a Sa galaxy. This spectrum is mainly dominated by evolved giant stars. However the appearance of emission lines such as [NII] 6548, 6583 Å and H, with equivalent widths of only a few angstroms, indicates the presence of a young stellar population. For the integrated spectra of this galaxy we measure EW(H + [NII]) = 8 Å.

ESO 266-G015: Although we could not take images of this galaxy, a preliminary examination can be made from the original prints of Agüero (1971). This is a peculiar galaxy with an irregular and very weak disk from which two filaments of different shape and size emerge. These filaments reassemble spiral arms, the southern being very wide and short, the northern thin and long. The nucleus is not located in the galaxy center.

The whole-aperture spectrum corresponds to a starburst galaxy showing strong H as well as [NII] 6548, 6583 Å [OII] 3727 Å, H, [OI] 6300 Å, and [SII] 6717, 6731 Å emission lines. The similar observed values of EW(H + [NII]) in both nuclear and integrated spectra indicates that this galaxy is under a global starburst (see Table 7 (click here)).

ESO 340-G021: From a visual inspection of the B image shown in Fig. 1 (click here)f we may conclude that this is a normal Sb galaxy. It shows a stellar-nucleus and a very bright disk when compared to the arms. The arms are somewhat weak in the blue and more prominent in the red.

The luminosity profiles shown in Fig. 2 (click here)e, exhibit the same trend in all bands indicating an homogeneous color throughout the galaxy. The profiles are clearly disk dominated and the observed excess in the exponential law for 5'' < r < 22'' is due to the contribution of the spiral arms.

Both nuclear and integrated spectra show the same signatures and, as in the case of NGC 3318, they correspond to a Sb galaxy (see Fig. 4 (click here)g). It can also be noted in the spectra a blue continuum from young stars and the G- and K-giant absorption features.

AM 2054-433N: In Fig. 1 (click here)g can be appreciated that this is a normal SO galaxy, and with AM 2054-433S is the only interacting system of the sample. From our images it is distinguished a faint stellar-nucleus from which emerges a small filament towards the NW. The disk is very prominent an it exhibits a shell-like structure in the S side.

The interesting V-I color map of this galaxy can be appreciated in Fig. 5 (click here). It shows three well different regions with rather uniform colors: an inner region (0'' < r < 15'') with (V-I) = 1.4, an intermediate region (15'' < r < 30'') with (V-I) =1.2 and the outer most region with the same color as the inner region. This remarkable structure could be signature of different events of stellar formation. Unfortunately we could not obtain the B-I and B-V color maps due to poor seeing in the B frame.

  
Figure 5: V-I color map of the galaxy AM 2054-433N. North is at top and East to the left. The lower left bar indicates 1 arcmin

The luminosity profiles (Fig. 2 (click here)f) show a weak bulge and a prominent disk with a feature located at r = 18'' in the B profile. In the V, R and I profiles this feature is present at r = 12''. This excess is more prominent in the blue and it fades through redder bands.

Although this galaxy had been previously classified by S&W as a LINER, we report a Seyfert 2 nucleus, as inferred from the line flux ratios calculated from the pure-emission spectrum (see Table 8 (click here)).

We trace the rotation curve of this galaxy up to a radius of 20 Kpc, and it can be seen from Fig. 3 (click here)d that the maximum velocity, corrected for the galaxy inclination (b/a = 0.5), is  km s^-1 at r = 5 kpc.

AM 2054-433S: We classify this object as a normal edge-on Sc galaxy as it can be judged from Fig. 1 (click here)g. This galaxy shows a bright stellar-nucleus and two well developed arms. The NE arm is larger than the SW and it can be noticed several blue knots, , and dust lanes. It can also be seen from Fig. 1 (click here)g that this galaxy exhibits a disk warped towards the SO galaxy, probably due to the interaction.

The luminosity profiles are rather uniform in all bands (see Fig. 2 (click here)g). Both the bulge and the disk of this galaxy are very prominent. Using the decomposition technique we obtain  Kpc and  Kpc.

The flux line ratios calculated from the pure emission spectrum indicate a LINER-type nucleus, as previously found by S&W.

From both H and [NII] emission lines we provide the rotation curve of this galaxy up to a radius of 40 kpc which is shown in Fig. 3 (click here)e. The rotation curve corrected for the galaxy inclination shows a maximum  km s ^-1 at r = 10 kpc. This high rotational velocity is similar to that corresponding to AM 2054-433 N.

IC 5325: From the B image shown in Fig. 1 (click here)h we conclude that this is a normal face-on Sb galaxy. The galaxy shows a stellar-nucleus from which several arms emerge. The arms are rather fragmented and they exhibit several blue knots with (B-V) = 0.2-0.6. The galaxy colors are rather uniform and the luminosity profiles are clearly disk dominated beyond r = 5'' (see Fig. 2 (click here)h).

The integrated spectrum of the galaxy shown in Fig. 4 (click here)j corresponds to a Sb type and we obtain EW(H + [NII]) = 20 Å, a typical value for this type of galaxies.