Environmental effects on the evolution of dwarf and spiral galaxies: dynamics and stellar populations

The work presented in this thesis is aimed at the observational characterization of the physical properties of galaxies to place constraints on their scenarios of formation and evolution. In particular, I have focused on the determination of how the environment in which galaxies evolve affects their structural and kinematic properties, and their stellar populations. In the first part of my thesis I studied the properties of the dwarf early-type galaxy population in two nearby galaxy clusters: Centaurus and Perseus. For the Centaurus Cluster, I analysed X-Shooter spectroscopy of a sample of eight dwarf elliptical galaxies and two compact elliptical galaxies. The visible arm high-resolution spectra were employed to derive the internal velocity dispersion of the galaxies, together with an estimate of their dynamical mass and their mass-to-light ratios. I used the internal velocity dispersion measurements to compute the first estimate of the Faber-Jackson relation of dwarf galaxies in the Centaurus Cluster. I used the medium resolution optical spectra to characterize the stellar populations of the dwarf and compact galaxies. In addition, I analysed fibre spectroscopic data of low-luminosity ellipticals in the Perseus Cluster. My investigation of the global cluster kinematics confirmed the different origin of the faint galaxy population with respect to the bright galaxies. Measurements of the properties of the stellar populations were performed on all the cluster early-type galaxies, and were used to derive the first estimate of the mass-metallicity relation for the Perseus Cluster. In the second part of my thesis I analysed the stellar populations of a sample of bulges in twelve isolated disc galaxies and in four spiral galaxies with a high surface brightness disc. I derived the structural parameters of the bulges by performing two-dimensional photometric decomposition of galaxy images. I analysed long-slit spectroscopy to derive the age, metallicity, and \afe\ enhancement in the central part of the bulge and at the radius where the bulge contributes the same surface brightness as the other galaxy components. The bulges of isolated galaxies are characterized by intermediate and old ages, a large spread in metallicities ranging from sub- to super-solar values, and super-solar [α/Fe] enhancements. The high [α/Fe] ratios indicates shorter star formation timescales with respect to galaxies in denser environments. All the sample bulges also show a negative gradient for the [α/Fe] enhancement, in agreement with the predictions of the dissipative collapse formation scenario. By comparing our analysis with those of selected samples from the literature, I was able to confirm that environment-driven processes play an important role in the evolution of bulges in high density environments. In particular, repeated interactions and merging with other galaxies tend to erase the stellar population gradients of the bulges and prolong their star formation histories