Aims. Previous studies have indicated that faint and bright early-type galaxies (ETGs) present different coefficients and dispersions for their Kormendy relation (KR). A recently published paper states that the intrinsic dispersion of the KR depends on the magnitude range within which the galaxies are contained, therefore we investigate here whether the magnitude range also has an influence on the values of the coefficients of the KR: α (zero point) and β (slope). If the values of the KR coefficients depend on the magnitude range, and this fact is not considered when performing comparisons of different galaxy samples, the differences which might be found may be misinterpreted. Methods. We perform an analysis of the KR coefficients for 4 samples of galaxies, which contain an approximate total of 9400 ETGs in a relatively wide magnitude range ( ΔM ∼ 6 mag). We calculate the values of the KR coefficients in two ways: i) we consider the faintest galaxies in each sample and we progressively increase the width of the magnitude interval by inclusion of the brighter galaxies (increasing magnitude intervals); and ii) we consider narrow magnitude intervals of the same width (ΔM = 1.0 mag) over the whole magnitude spectrum available (narrow magnitude intervals). We also perform simulations of the distribution of galaxies in the log(r e ) − μ e plane and compare the KR defined by the simulations with that obtained from the real galaxy samples.Results. The main results we find are as follows: i) in both increasing and narrow magnitude intervals the KR coefficients change systematically as we consider brighter galaxies; ii) non-parametric tests show that the fluctuations in the values of slope of the KR are not products of chance variations and that there is evidence of an underlying trend; and iii) this trend suggest a maximum of the slope around absolute magnitude M B ∼ −18 ± 1. Conclusions. We conclude that the values of the KR coefficients depend on the width of the magnitude range and the brightness of galaxies within the magnitude range. This dependence is due to the fact that the distribution of galaxies in the log(r e ) − μ e plane depends on luminosity and that this distribution is not symmetrical, that is, the geometric shape of the distribution of galaxies in the log(r e ) − μ e plane plays an important role in the determination of the values of the coefficients of the KR.

We present a stellar population study of three H ii galaxies (Mrk 36, UM 408, and UM 461) based on the analysis of new ground-based high-resolution near-infrared J, H, and K p broadband and Brγ narrowband images obtained with Gemini/NIRI. We identify and determine the relative ages and masses of the elementary star clusters and/or star cluster complexes of the starburst regions in each of these galaxies by comparing the colors with evolutionary synthesis models that include the contribution of stellar continuum, nebular continuum, and emission lines. We found that the current star cluster formation efficiency in our sample of low-luminosity H ii galaxies is ∼10%. Therefore, most of the recent star formation is not in massive clusters. Our findings seem to indicate that the star formation mode in our sample of galaxies is clumpy, and that these complexes are formed by a few massive star clusters with masses 10 4 M . The age distribution of these star cluster complexes shows that the current burst started recently and likely simultaneously over short timescales in their host galaxies, triggered by some internal mechanism. Finally, the fraction of the total cluster mass with respect to the low surface brightness (or host galaxy) mass, considering our complete range in ages, is less than 1%.

Aims. Previous studies have found that the coefficients and intrinsic dispersions of both the Kormendy relation and the Fundamental Plane depend on the magnitude range within which the galaxies are contained. We study whether this type of behaviour is also present for the Faber-Jackson relation. Methods. We take a sample of early-type galaxies from the Sloan Digital Sky Survey (SDSS-DR7, ∼90 000 galaxies) spanning a range of approximately 7 mag in both g and r filters and analyse the behaviour of the Faber-Jackson relation parameters as functions of the magnitude range. We calculate the parameters in two ways: i) we consider the faintest (brightest) galaxies in each sample and we progressively increase the width of the magnitude interval by inclusion of the brighter (fainter) galaxies (increasing-magnitudeintervals); and ii) we consider narrow-magnitude intervals of the same width (ΔM = 1.0 mag) over the whole magnitude range available (narrow-magnitude-intervals). Results. Our main results are that: i) in both increasing and narrow-magnitude-intervals the Faber-Jackson relation parameters change systematically, ii) non-parametric tests show that the fluctuations in the values of the slope of the Faber-Jackson relation are not products of chance variations. Conclusions. We conclude that the values of the Faber-Jackson relation parameters depend on the width of the magnitude range and the luminosity of galaxies within the magnitude range. This dependence is caused, to a great extent by the selection effects and because the geometrical shape of the distribution of galaxies on the M − log(σ 0 ) plane depends on luminosity. We therefore emphasize that if the luminosity of galaxies or the width of the magnitude range or both are not taken into consideration when comparing the structural relations of galaxy samples for different wavelengths, environments, redshifts and luminosities, any differences found may be misinterpreted.

Using GMOS–IFU spectroscopic observations of the compact H ii/blue compact dwarf galaxies Tol 0104−388 and Tol 2146−391, we study the spatial distribution of emission lines, equivalent width EW(Hβ), extinction c(Hβ), ionization ratios ([O iii] λ5007/Hβ, [S ii] λλ6717, 6731/Hα and [N ii] λ6584/Hα), kinematics and the chemical pattern (O/H, N/H and N/O) of the warm interstellar medium in these galaxies. We also investigate a possible dependence of these properties on the I(He ii λ4686)/I(Hβ) ratio and find no significant correlation between these variables. In fact, the oxygen abundances appear to be uniform in the regions where the He ii λ4686 emission line was measured. It can be interpreted in the sense that these correlations are related to global properties of the galaxies and not with small patches of the interstellar medium. Although a possible weak N/H gradient is observed in Tol 2146−391, the available data suggest that the metals from previous star formation events are well mixed and homogeneously distributed through the optical extent of these galaxies. The spatial constancy of the N/O ratio might be attributed to efficient transport and mixing of metals by starburst‐driven supershells, powered by a plethora of unresolved star cluster in the inner part of the galaxies. This scenario agrees with the idea that most of the observed He ii λ4686 emission line is produced by radiative shocks, although other sources such as Wolf Rayet stars, high mass X‐ray Binaries and O stars cannot be excluded.

Using VIMOS-IFU observations, we study the interstellar medium (ISM) of two star-forming dwarf galaxies, UM 461 and Mrk 600. Our aim was to search for the existence of metallicity inhomogeneities that might arise from infall of nearly pristine gas feeding ongoing localized star-formation. The IFU data allowed us to study the impact of external gas accretion on the chemical evolution as well as the ionised gas kinematics and morphologies of these galaxies. Both systems show signs of morphological distortions, including cometary-like morphologies. We analysed the spatial variation of 12 + log(O/H) abundances within both galaxies using the direct method (T e ), the widely applied HII-CHI-mistry code, as well as by employing different standard calibrations. For UM 461 our results show that the ISM is fairly well mixed, at large scales, however we find an off-centre and low-metallicity region with 12 + log(O/H) < 7.6 in the SW part of the brightest H ii region, using the direct method. This result is consistent with the recent infall of a low mass metal-poor dwarf or H i cloud into the region now exhibiting the lowest metallicity, which also displays localized perturbed neutral and ionized gas kinematics. Mrk 600 in contrast, appears to be chemically homogeneous on both large and small scales. The intrinsic differences in the spatially resolved properties of the ISM in our analysed galaxies are consistent with these systems being at different evolutionary stages.