We performed K band surface photometry for luminous early-type galaxies in a nearby rich cluster ABELL 2199 .
Combining it with B and R band surface photometry , radial variations of B - R and R - K colours in the galaxies were investigated .
It is found that the inner regions of the galaxies are redder in both of B - R and R - K colours .
Comparing the radial variations of both of the colours with predictions of Simple Stellar Population ( SSP ) models for a range of ages and metallicities , it is suggested that the cluster ellipticals have negative metallicity gradients but their age gradients are consistent with zero , although our sample is small ; the typical metallicity gradient is estimated to be -0.16 \pm 0.09 in d \log Z / d \log r , while the age gradient is estimated to be -0.10 \pm 0.14 in d \log { ( age ) } / d \log r .
Considering that similar results have also been derived in the other recent studies using samples of ellipticals in the Coma cluster and less dense environments , it seems that there is no strong dependence on galaxy environment in radial gradient of stellar population in elliptical galaxy .