TITLE:  Strong radial segregation of evolutionary homogeneous populations of stars in intermediate-mass Galactic globular 
clusters.

 

ABSTRACT:

An adequate knowledge of the properties of stellar populations at different radial distance in Galactic globular clusters (GGCs) 
can shed more light on the formation and dynamical evolution of these keystone objects. In the present contribution we 
summarize our recent results obtained on the inhomogeneity (multiplicity) of stellar populations in three intermediate-mass 
Galactic globular clusters (GGCs), NGC 1261, NGC 3201, and NGC 6752. We rely on ground-based multicolor photometry 
including measurements in the valuable U band in extended (14’x14’) fields of these GGCs. First, we find for the first time a 
strong radial segregation, especially pronounced in the nearby GGC NGC 6752, between the sub-populations of red giant 
branch (RGB) stars bluer and redder in the color U-B, as well as between sub-giant branch (SGB) stars brighter and fainter in 
the U-magnitude. Moreover, both fainter SGB and redder RGB stars are similarly more centrally concentrated than their 
brighter and bluer counterparts, respectively. Second, a dramatic change in the proportion of the two mentioned 
sub-populations of SGB and RGB stars in NGC 6752 and NGC 3201 occurs at a radial distance very close to their half-mass 
radius, R_h. Thanks to U-photometry extending well below the turnoff point in the GGC NGC 6752, we find the same radial 
segregation between main sequence stars bluer and redder in the U-B color.