The workshop proposed here is the ideal way to accomplish all of these aims. It intends to bring together world-leading experts in studies of massive stars and violent star formation, both from the observational and the theoretical points of view. This will be a novel approach, in the sense that this workshop will combine the collective expertise of a large number of experts with a collective broad experience instead of the usual small mono and bilateral collaborations that naturally only contemplate one or the other facet of the problem.
More specifically, we have identified five key areas (and possible leaders) to be addressed by the workshop, including:
Proposed participants of the workshop are well placed to play a leading role in the targetted field. There is a tradition of excellence and world leadership among our participants in areas such as stellar evolution and stellar atmospheres as well as galactic chemical evolution, studies of the physics of violent star forming regions (such as giant HII regions and HII galaxies), their chemical composition, stellar population, photoionisation models, gas and stellar dynamics, studies and models of W-R stars and their environment, N-body dynamical simulations of the evolution of young stellar clusters, hydrodynamical studies of regions of star formation and galaxy evolution.
The science goals we plan to address require the combined expertise and synergy of multiple teams. The time is ripe to bring together this collective expertize in a brain storming effort to discuss some of the most pressing problems of violent and massive star formation and evolution, and their implication for galaxy formation and evolution.
The understanding of the formation and evolution of galaxies is a key issue in contemporary astrophysics and cosmology. Large ground-based facilities and sophisticated space-based observatories allow the careful scrutiny of distant galaxies, thus allowing us a view back at a time when the Universe was only a fraction of its present age, when most galaxies were still extremely young. However, it has become clear that in order to understand the evolution of galaxies it is essential to understand the detailed physics of their main components, i.e., the massive young stellar clusters, and their interaction with the environments from which they originated and in which they are immersed.
Strong evidence that massive stars formed copiously in the redshift
range from 1 to 2 is provided, predominantly, by optical spectroscopy.
This observational evidence implies conclusively that the star formation
rate was at least an order of magnitude higher at those redshifts than
at present. Similarly, the observed Lyman 
emission-line profiles associated with blue-shifted interstellar absorption
lines in high-redshift star-forming galaxies imply the presence of powerful
galactic winds, which - in turn - suggests a close interaction between
the ejecta from massive stars (i.e., stellar winds and supernovae) and
the interstellar medium (ISM) of their host galaxies.
Finally, observations at millimeter waves of very high redshift quasars
indicate that at z
4
large masses of dust were already in place, suggesting that at a time when
the Universe was still very young a substantial amount of astration had
already taken place.
The role of massive stars and their energetics is therefore central to the understanding of galaxy evolution. This implies the need for profound studies to eventually understand how massive stars affect their environment and, vice versa, how the environment influences the star formation and evolution, and galaxy evolution in general. The novel and very timely approach in this field is to recognise the complex interplay between the gaseous and stellar components, and hence cannot be understood if one considers these components separately. Central to the problem is to consider their non-linear interactions. Many of the most fundamental problems in star cluster formation and evolution seem to be on the verge of solution by combining observations with theoretical modeling that integrates stellar evolution, stellar dynamics, gas dynamics and chemical evolution, as well as the microphysics implicit in photo and collisional ionisation, radiative transfer, diffusion, dust formation and mixing, to name a few.
Outstanding and crucial is the problem of the feedback processes associated with star formation, their nature, and their relation to the environmental properties. Feedback is believed to be the key mechanism that could largely and predominantly affect the aggregation of luminous matter, as opposed to that of dark matter. Differential effects of feedback during galaxy formation may also be the cause of a number of properties of local spheroids, such as the colour-magnitude relation, the sequence of narrow-band indices, the UV rising branch and the fundamental plane of early-type galaxies. Understanding the physics of feedback from massive stars implies the need for a thorough analysis of their life cycle, from their condensation within molecular clouds to their initial mass function, the efficiency of their birthrate, as well as their energetics. Furthermore, all of these issues will have to be contemplated within the framework of their interaction with the surrounding medium, either the circumstellar gas, or the interstellar and intergalactic media.
Crucially for the astronomical community at large, we plan to begin to develop a sophisticated open-source software tool (the ``Legacy Tool'') that will incorporate theoretical high-resolution synthesis models of stellar populations, chemical evolution, abundance determination and chemo-dynamical models and the possibility of applying them to heterogeneous databases. This will be an invaluable legacy in the sense that it will bring many dispersed efforts into a single access mode that will guide the user via a user-friendly interface. This task is a complex and highly challenging task in computer science, and will be an asset provided by the targeted and highly specialised expertise of the Computer Science Department at INAOE. Novel and newly developed techniques involved will be sufficiently general as to be applicable to other scientific and industrial domains outside of astronomy as such. In this framework, we also plan to establish a centre for stellar atmospheres calculations (Stellar atmospheres Laboratory) which will represent a long term investment, as the relatively costly computing hardware needed will also be utilised later by other Institute projects. The Laboratory will be presented in more detail below.
The science goals we plan to address require the combined expertise and synergy of multiple teams. The time is ripe to bring together this collective expertize in a brain storming effort to discuss some of the most pressing problems of violent and massive star formation and evolution, and their implication for galaxy formation and evolution.