We review the results from our studies, and previous published work, on the spatially resolved physical properties of a sample of HII/BCD galaxies, as obtained mainly from integral-field unit spectroscopy with Gemini/GMOS and VLT/VIMOS. We confirm th
at, within observational uncertainties, our sample galaxies show nearly spatially constant chemical abundances, similar to other low-mass starburst galaxies. They also show He II 4686 emission with properties being suggestive of a mix of excitation sources, with Wolf-Rayet stars being excluded as the primary one. Finally, in this contribution we include a list of all HII/BCD galaxies studied thus far with integral-field unit spectroscopy.
We present Integral Field Unit GMOS-IFU data of the compact HII galaxy UM408, obtained at Gemini South telescope, in order to derive the spatial distribution of emission lines and line ratios, kinematics, plasma parameters, and oxygen abundances as w
ell the integrated properties over an area of 3x4.4(~750x1100 pc) located in the central part of the galaxy. The starburst in this area is resolved into two giant regions of ~375 and 250pc diameter, respectively. The ages of these two regions, estimated using Hb equivalent widths, suggest that they are coeval events of ~5Myr with stellar masses of ~10^4M_o. We have also used [OIII]/Hb and [SII]/Ha ratio maps to explore the excitation mechanisms in this galaxy. The Ha emission line was used to measure the radial velocity and velocity dispersion. We derived an integrated oxygen abundance of 12+log(O/H)=7.87 summing over all spaxels in our field of view. An average value of 12+log(O/H)=7.77 and a difference of D(O/H)=0.47 between the minimum and maximum values (7.58+-0.06-8.05+-0.04) were found, considering all data points where the oxygen abundance was measured. The spatial distribution of oxygen abundance does not show any significant gradient across the galaxy. On the other hand, the bulk of data points are lying in a region of +-2sigma dispersion (with sigma=0.1 dex) around the average value, confirming that this compact HII galaxy as other previously studied dwarf irregular galaxies is chemically homogeneous. Therefore, the new metals processed and injected by the current star formation episode are possibly not observed and reside in the hot gas phase, whereas the metals from previous events are well mixed and homogeneously distributed through the whole extent of the galaxy.
