PROFESSOR RUSSELL CANNON

Blue Straggler stars were first discovered by Alan Sandage in the globular cluster M3, in 1953. They appear to be younger than the bulk of the stars in a cluster, lying on the main sequence but above the turn-off point that measures a cluster's age. 60 years later we are still trying to understand their evolution and significance. Long regarded as a fascinating but relatively minor feature of stellar evolution, it has gradually become apparent that they can be a major factor in the dynamical evolution of clusters, as well as perhaps contributing significantly to the integrated light and spectra of distant galaxies. A fundamental problem is that there have been many proposed mechanisms to create Blue Stragglers and it seems that several of these are valid: the class of objects is not well-defined and defies Ockhams Razor (Livio, at a 1992 STScI Workshop). ESO recently organised another Workshop on Blue Stragglers, in Santiago in November 2012. The speaker will review the early history of the field and try to summarise the current state of our knowledge, based on the ESO Workshop.