Near-Infrared Properties of Metal-poor Globular Clusters in the Galactic
  Bulge Direction
  Aims. J, H, and K' images obtained from the near-infrared imager CFHTIR on
the Canada-France-Hawaii Telescope are used to derive the morphological
parameters of the red giant branch (RGB) in the near-infrared color-magnitude
diagrams for 12 metal-poor globular clusters in the Galactic bulge direction.
Using the compiled data set of the RGB parameters for the observed 12 clusters,
in addition to the previously studied 5 clusters, we discuss the properties of
the RGB morphology for the clusters and compare them with the calibration
relations for the metal-rich bulge clusters and the metal-poor halo clusters.
Methods. The photometric RGB shape indices such as colors at fixed magnitudes
of MK = MH = (-5.5, -5, -4, and -3), magnitudes at fixed colors of (J - K)o =
(J - H)o = 0.7, and the RGB slope are measured from the fiducial normal points
defined in the near- infrared color-magnitude diagrams for each cluster. The
magnitudes of RGB bump and tip are also estimated from the differential and
cumulative luminosity functions of the selected RGB stars. The derived RGB
parameters have been used to examine the overall behaviors of the RGB
morphology as a function of cluster metallicity. Results. The correlations
between the near-infrared photometric RGB shape indices and the cluster
metallicity for the programme clusters compare favorably with the previous
observational calibration relations for metal-rich clusters in the Galactic
bulge and the metal-poor halo clusters. The observed near-infrared magnitudes
of the RGB bump and tip for the investigated clusters are also in accordance
with the previous calibration relations for the Galactic bulge clusters.
