16361

The distribution of core radius (rc) versus chronological age for the globular clusters (GCs) in the Large Magellanic Cloud (LMC) is very peculiardoublePoint old GCs show a large spread in rc comma while young clusters are all compact. The origin of such a distribution is largely debated and mostly interpreted in terms of an evolutionary sequencedoublePoint all GCs formed with compact cores (rc<3 pc) comma then most of them maintained small cores comma while several others experienced core expansion due to the heating action of binary black holes. This scenario is becoming the new paradigm of GC formation and evolution. However a new and more natural interpretation could existdoublePoint the spread in rc observed at fixed chronological age could be due to different levels of dynamical evolution (dynamical ages) comma with large-core GCs being dynamically-younger than those with small rc. This alternative scenario can now be tested since the level of dynamical evolution reached by a star cluster can be empirically measured from the level of central segregation of its Blue Straggler Star population. Here we propose deep WFC3 observations of 3 of the most compact (rc<0.8 pc) comma old comma and still unexplored GCs in the LMC comma to determine their dynamical age and definitely confirm this scenario. The scientific return of the project is hugedoublePoint in fact comma the correct interpretation of the rc-age distribution would not only shed light on the correct paradigm for GC formation comma but would also raise new fundamental questions concerning the processes responsible for the observed differences between the structural properties of old and young LMC GCs. Because of the legacy value of the proposed observations comma we waive the proprietary period.