Near-Infrared Imaging of the Central Regions of Metal-Poor Inner Spheroid Globular Clusters

JHK images obtained with the Canada-France-Hawaii Telescope (CFHT) AdaptiveOptics Bonnette (AOB) are used to investigate the near-infrared photometricproperties of red giant branch (RGB) and horizontal branch (HB) stars in eightmetal-poor globular clusters with R_GC < 2 kpc. The slope of the RGB on the (K,J-K) CMDs confirms the metal-poor nature of these clusters, four of whichappear to have metallicities comparable to M92. The luminosity functions of RGBstars in inner spheroid and outer halo clusters have similar slopes, althoughthere is a tendency for core-collapsed clusters to have slightly flatterluminosity functions than non-collapsed clusters. The distribution of red HBstars on the (K, J-K) CMDs of inner spheroid clusters with [Fe/H] ~ -1.5 isvery different from that of clusters with [Fe/H] ~ -2.2, suggesting thatmetallicity is the main parameter defining HB content among these objects. TheRGB-bump is detected in four of the inner spheroid clusters, and this featureis used to compute distances to these objects. Finally, the specific frequencyof globular clusters in the inner Galaxy is discussed in the context of theearly evolution of the bulge. If the globular cluster formation efficiency forthe inner Galaxy is similar to that measured in other spheroidal systems, thenthe main body of the bulge could have formed from gas that was chemicallyenriched in situ.Comment: 26 pages of text and 13 postscript figures. To appear in the Astronomical Journa