Radial Dependence of the Proto-Globular Cluster Contribution to the
  Milky Way Formation
  Recent interpretation of the color$-$magnitude diagrams of the Milky Way (MW)
bulge has suggested that the observed double red-clump feature can be a natural
consequence of He-enhanced stellar populations in the MW bulge. This implies
that globular clusters (GCs), where the He-enhanced second-generation (SG)
stars can be efficiently created, are the most likely candidate contributors of
He-rich stars to the MW bulge. We extend this idea to the Galactic inner halo
and investigate the fraction of the SG stars as a function of the
Galactocentric distance. We use bluer blue-horizontal branch (bBHB) stars,
which are assumed to be originated from He-rich SG populations, as proxies of
SG stars, and find that the fraction of bBHB stars increases with decreasing
Galactocentric distance. Simulations of the GC evolution in the MW tidal field
qualitatively support the observed trend of bBHB enhancement in the inner halo.
In these simulations, the increasing tidal force with decreasing Galactocentric
distance leads to stripping of stars not only from the outskirts but also from
the central regions of GCs, where SG stars are more abundant. We discuss the
implication and prospect of our findings concerning the formation history of
the bulge and inner halo of the MW.
