Wide-field JHKs images obtained with the SIRIUS near-infrared camera of the IRSF 1.4m telescope are used to examine the tidal structures of the spatial stellar configuration around six metal-poor ([Fe/H]< −1.0) globular clusters located within 3 kpc from the Galactic center. The radial surface density profiles are obtained from the surface photometry of the cluster images and the star counting for the photometric data. For the star counting, candidates of cluster member stars are selected with an filtering algorithm in color-magnitude diagrams. We find that the six target clusters show tidal overdensity features in the radial surface density profiles. There is a break inside the tidal radius for each cluster, and the profile in the outer overdensity region is characterized by a power law. Two- dimensional density maps of all the clusters show distorted asymmetric stellar configurations in the outer region. In five out of the six target clusters, the overdensity features are likely to be associated with the effects of the Galaxy dynamical interaction and the cluster space motions. The observed tidal configurations of stars suggest that several metal-poor clusters in the Galactic bulge are possibly surviving remnants of mergers to build the old stellar system of the Galactic bulge.

We have studied the environmental effect on optical-NIR color gradients of 273 nearby elliptical galaxies. Color gradient is a good tool to study the evolutionary history of elliptical galaxies, since the steepness of the color gradient reflects merging history of early types. When an elliptical galaxy goes through many merging events, the color gradient can be get less steep or reversed due to mixing of stars. One simple way to measure color gradient is to compare half-light radii in different bands. We have compared the optical and near infrared half-light radii of 273 early-type galaxies from Pahre (1999). Not surprisingly, we find that re(V)s (half-light radii measured in V-band) are in general larger than re(K)s (half-light radii measured in K-band). However, when divided into different environments, we find that elliptical galaxies in the denser environment have gentler color gradients than those in the less dense environment. Our finding suggests that elliptical galaxies in the dense environment have undergone many merging events and the mixing of stars through the merging have created the gentle color gradients.