COLOR-MAGNITUDE DIAGRAMS OF MERGED GLOBULAR-CLUSTERS - METALLICITY EFFECTS

Mergers of globular clusters (GCs) once associated with dwarf spheroid al (dSph) galaxies have recently been suggested as an explanation for the bimodal horizontal branches (HBs) of some Galactic GCs, most notab ly NGC 1851, NGC 2808, and NGC 6229. Through analysis of the available color-magnitude diagrams for the GCs in the Fornax and Sagittarius dS PH satellites of the Milky Way, as well as their metallicity distribut ions, we argue that the merger of two GCs would most likely produce a bimodal distribution in red giant branch (RGB) colors, or at least a s ignificant broadening of the RGB, because of the expected difference i n metallicity between the two merging globulars. No GC with a bimodal RGB is currently known, and the tightness of the RGB sequences in the above bimodal HE GCs implies that a merger origin for their HE bimodal ity is unlikely.