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Abstract

Many possible scenarios for the formation of multiple stellar populations
(MSP) in globular clusters (GCs) have been discussed so far, including the
involvement of asymptotic giant branch stars, fast rotating main sequence
stars, very massive main sequence stars and mass-transferring massive binaries
based on stellar evolution modelling. But self-consistent, dynamical
simulations of very young GCs are usually not considered. In this work, we
perform direct $N$-body modelling such systems with total masses up to
$3.2\times10^5$ M$_\odot$, taking into account the observationally constrained
primordial binary properties, and discuss the stellar-mergers driven both by
binary stellar evolution and dynamical evolution of GCs. The occurrence of
stellar mergers is enhanced significantly in binary-rich clusters such that
stars forming from the gas polluted by mergers-driven ejection/winds would
appears as MSPs. We thus emphasize that stellar mergers can be an important
process that connects MSP formation with star cluster dynamics, and that
multiple MSP formation channels can naturally work together. The scenario
studied here, also in view of a possible top-heavy IMF, may be particularly
relevant for explaining the high mass fraction of MSPs (the mass budget
problem) and the absence of MSPs in young and low-mass star clusters.