Resumen de Estudio diferencial de procesos de formación estelar en regiones HII de disco internas y externas de galaxias espirales cercanas
Marina Rodriguez Baras
Despite the observationally inferred different physical properties of HII regions located in inner and outer zones of galaxy disks, the general methods applied to the study of star-forming processes and the estimation of abundances have been derived from observations of intermediate disk regions, and assumed to be valid for regions over the whole galactic disks. However, the advent of Integral Field Spectroscopy (IFS) has provided access to large samples of spatially resolved, high-quality and homogeneous data from HII regions across the whole surface of galaxy disks. This allows for the first time the characterisation and comparison of these extreme regions physical properties, generating key information for galaxy formation theories and chemical evolution models. Within this context, the main goal of this thesis is the differential study of two large samples of inner and outer HII regions observed with IFS, in order to explore the existence of intrinsic differences in the star-forming processes as a function of the region location and the environment.
Some of the main results obtained are the following: Inner region ionising clusters are found to have higher metallicities and larger masses, and to a certain extent seem to be in a later evolution state with respect to outer regions. Inner regions show higher [NII]/[OII] values and lower [OII]/[OIII] than predicted by models. These differences affect the suitability and/or the reliability range of oxygen abundance and ionisation parameter calibrations based on several strong emission-line ratios, specially when inner regions are considered. Both inner and outer regions have composite stellar populations (ionising and non-ionising), according to their B-V colours. Overall, this work confirms the existence of intrinsic differences between regions as a function of their location across the galactic disks, as well as the influence that these differences may have on the methods generally applied to the study of HII regions and, in a wider context, to the determination of radial gradients and spatially resolved galactic properties.
