On the star formation efficiencies and evolution of multiple stellar
  generations in Globular Clusters
  By adopting empirical estimates of the Helium enhancement (Delta Y) between
consecutive stellar generations for a sample of Galactic globular clusters
(GGC), we uniquely constraint the star formation efficiency of each stellar
generation in these stellar systems. In our approach, the star formation
efficiency is the central factor that links stellar generations as it defines
both their stellar mass and the remaining mass available for further star
formation, fixing also the amount of matter required to contaminate the next
stellar generation. In this way, the star formation efficiency is here shown to
be fully defined by the He enhancement between successive stellar generations
in a GC.
  Our approach has also an impact on the evolution of clusters and thus
considers the possible loss of stars through evaporation, tidal interactions
and stellar evolution. We focus on the present mass ratio between consecutive
stellar generations and the present total mass of Galactic globular clusters.
Such considerations suffice to determine the relative proportion of stars of
consecutive generations that remain today in globular clusters. The latter is
also shown to directly depend on the values of Delta Y and thus the He
enhancement between consecutive stellar generations in GGC places major
constraints on models of star formation and evolution of GC.
