ESTALLIDOS
Multifaced study of star-formation in the Universe (Estallidos 8)

The process of massive star formation can be intimately related to the environment where it takes place. From the origin of the first stars, at the end of the cosmic dark ages, up to the last steps in the life of massive stars in nearby HII regions, stars form out of gas which is structured in a given distribution. Thus, triggering mechanisms and evolution of star formation are linked to the environment.

Therefore the "Nature versus Nurture" dilemma has a special relevance in the study of massive star formation in different environments. From our close environment, in the neighborhood of the Milky Way, up to the population of star-forming galaxies in clusters, it is now well stablished that the role played by the environment is a key factor for the study of the evolution of galaxies.

From theoretical grounds, it is expected that galaxies located in high density regions, such as clusters or groups, may suffer from strong environmental effects (e.g. tidal interactions, interactions with other galaxies and with the intracluster medium [ICM], etc.) giving rise to processes of mass redistribution or even producing a certain degree of morphological evolution, e.g. the so-called "Harassment" scenario. At this point, quantitative morphology studies and/or rather direct estimations of the SFR in cluster galaxies can help constraining different models.

The interaction of galaxies with the ICM implies that their gaseous component is affected by ram pressure stripping and/or evaporation. In this respect, gas stripping and pressure confinement of the interstellar medium (ISM) will be also relevant for the study of the chemical evolution. Observational results show significant differences in the observable HI content between cluster and field spirals, the cluster ones being HI deficient. However, the results obtained for molecular clouds located near the center of these galaxies show that they remain not much affected in the discs. Given that gas-rich star-forming galaxies can be somewhat more fragile systems, the impact of the environment will be significant for these objects.

From the observational point of view, all these effects of the environment on the star formation activity in galaxies are expected to be significant and widely observable with present day instrumentation. This fact is then of a particular relevance for our project "Estallidos". Given the strong implications for the study of the evolution of galaxies we have focused on this topic our workshop in Granada.