Posters abstracts 45 Author(s): P. Alpresa (Univ. Autonoma de Madrid, Spain), R. Domínguez-Tenreiro (Univ. Autonoma de Madrid), F. Martinez-Serrano (Univ. Miguel Hernández, Elche, Spain), J. Oñorbe (Univ. Autonoma de Madrid, Spain), A. Serna (Univ. Miguel Hernández, Elche, Spain) Title: Isolated galaxies vs galaxies in groups: a study of their properties from cosmological simulations Abstract: Galaxies formed in cosmological simulations have been identified at different environments, either isolated or in groups. We report on a study of massive galaxy properties at different redshifts, to try to understand how the environment affects them at different epochs of their assembly and/or evolution. 58 Author(s): B. Ascaso (Physics Department, University of Davis, USA / IAA-CSIC, Spain), J. A. L. Aguerri (IAC, Spain), M. Moles (IAA-CSIC, Spain), R. Sánchez-Janssen (IAC, Spain), D. Bettoni (INAF-Osservatorio Astronomico di Padova, Italy) and G. Fasano (INAF-Osservatorio Astronomico di Padova, Italy) Title: The bright galaxy population of five medium redshift clusters. Quantitative Galaxy Morphology Abstract: Following the study based on the Nordic Optical Telescope (NOT) sample, which consists on five clusters of galaxies within the redshift range 0.15<0.25, imaged within the central 0.5-2 Mpc in very good seeing conditions, we have studied the quantitative morphology of their bright galaxy population. The surface brightness profiles of the galaxies have been decomposed in the bulge and disc photometrical components. Previously, we have performed simulations in order to check the reliability of the fits. These data allow us to derive a quantitative morphological classification of the galaxies, which has been compared with the previous visual one. Galaxies in clusters at this range of redshift do not present appreciable evolution for the bulges scales. However, their disc scales are different from those galaxies placed in clusters at low redshift and more similar to the field galaxies at low redshift. This result suggests that the evolution of the disc component in galaxy clusters is faster than in field ones, especially for the smaller ones. We will also compare these results with deeper samples of galaxies from Deep Lens Survey (DLS). Fast galaxy-galaxy encounters or interactions with the global gravitational potential are pointing to be the mechanisms responsible of this evolution in the last 2.5 Gyr. 3 Author(s): G. Bergond (IAA-CSIC / Calar Alto Observatory, Spain), S. Verley (UNAM, Mexico / IAA-CSIC, Spain), L. Verdes-Montenegro (IAA-CSIC, Spain) and the AMIGA team Title: The AMIGA Hα imaging survey of isolated spiral galaxies Abstract: We present an imaging survey of the Hα emission in ~200 isolated spirals selected from the AMIGA sample of isolated galaxies. Most data have been obtained with the 1.5-m Sierra Nevada Observatory telescope. Data reduction and analysis are detailed, as well as preliminary results for a subsample of these galaxies, aimed at providing a local reference for star formation studies in denser environments.