Reading the book of Globular Clusters with the lens of Stellar Evolution
Reading the book of Globular Clusters with the lens of Stellar Evolution – Globular Cluster studies are essential for a number of active topics in Astrophysics and Cosmology. Given their old age and their spatial distribution, these self-gravitating objects provide useful information on the modes with which Galaxies assemble and evolve. The presence of stars of various masses, and in different evolutionary phases, turn Globular Clusters into a living laboratory, where a number of issues related to stellar evolution theory can be investigated. No other stellar aggregate offers the unique opportunity of harbouring contemporary main sequence stars and tiny, compact objects, at the last stages of their life. The considerable progress made in the domains of high-resolution photometry and multi-object spectroscopy has produced precise data, that raise many challenging issues for the understanding of the formation process of Globular Clusters, and of the structure and evolution of their member stars. In particular, it is now well extablished that most Globular Clusters harbour multiple stellar generations, a result stimulating a renewed and controversial debate on the modes with which these structures formed, and the nature of the possible polluters of the interstellar medium. Also, the characteristics of the member stars that can be determined with exquisite details have highlighted the limits of our understanding of stellar evolution and bring invaluable clues on internal stellar hydrodynamics.
Hence the idea of a meeting on the observational and theoretical aspects of the structure, formation, and evolution of Globular Clusters, with the programme centered around the following topical questions:
1) Evolution of observations of Globular Cluster stars, from the early Color Magnitude Diagrams, to current photometry and high-resolution spectroscopy. Where are we? What should we expect next?
2) Role of Globular Clusters as laboratories for stellar evolution studies: from the shape of the Main Sequence, to the morphology of the Horizontal Branch. What have we learnt about physical processes of stars from Globular Clusters? Is the “second-parameter” problem definitively solved? How well can we date Globular Clusters?
3) Compact objects in Globular Clusters, and the delicate interplay between the physical conditions of the stellar environment and the rate of production of compact objects. Can we now answer long standing questions, such as which properties of Globular Clusters affect the presence of millisecond pulsars, or what is the fraction of White Dwarfs locked in binary systems?
4) New challenging scenarios for the formation of Globular Clusters, invoked by the discovery of multiple populations. Are there any possibility of discriminating between the various hypotheses? How does the new paradigm impact our understanding of the chemical and dynamical features of various astrophysical systems from the local to the high redshift universe?