Photometric properties of dwarf galaxies in the Coma cluster: radial dependence

Photometric properties (effective surface brightness, effective radius, radial profile index, axis ratio, color, color gradient) of 328 galaxies in the Coma cluster fainter than R=15 mag are examined as a function of the distance from the cluster center. No significant gradient is found for the effective surface brightness, effective radius and radial profile index. The distribution of axis ratios shows a concentration of round galaxies at the cluster center in the magnitude range 16.5 < R < 18; most of these are found to be old and to have intermediate metal abundance, suggesting that they are nucleated dwarf ellipticals. On the other hand, we find a significant gradient in color, in the sense that galaxy colours become bluer with increasing distance from the cluster center. We conclude that this color gradient represents a metallicity gradient.