Birth, Evolution and Death of Stellar Clusters

Using our recently improved understanding of star cluster physics, we are now within reach of answering a number of fundamental questions in contemporary astrophysics. Star cluster physics has immediate bearing on questions ranging from the physical basis of the stellar ini-tial mass function – Do any O-type stars form in isolation? What is the relative importance of stochastic (random) star formation versus competitive accretion? – to the build-up of the most massive clusters – Does the cluster mass function differ in different types of galaxies? How and why do the most massive star clusters form in small dwarf galaxies and what does that imply for the build-up of larger cluster samples? What are the main observables one could (or should) use to try and distinguish among the various star- and cluster-formation scenarios? Newly emerging theoretical insights, novel high-quality observational data and the advent of the next generation of observational facilities offer significant promise to reach satisfactory and robust answers to the key outstanding questions in this field. 1 Preamble: Tertulias When I was first approached to lead a main ‘Tertulia ’ during the RIA workshop on Stellar Clusters and Associations, I was rather puzzled by the invitation, to say the least. Although this expression may be commonplace to some, it is not outside of the Spanish-speaking diaspora. Fortunately, our trusted friend Wikipedia1 offered answers: tertulias were originally informal, social literary or artistic get-togethers, particularly in Latin cultural contexts, often (but not always) held in public places. In relation to this conference, however, the organisers meant me to chair an open discussion on outstanding questions in contemporary star cluster-related astrophysics. In the following, I aim at setting the scene for the discussion that followed, which I attempt to summarise in general terms. The lively exchange of new (and some old) ideas that ensued led, I believe, to a general broadening of participants ’ perspectives – in the true sense of the traditional tertulia