Wide Field CCD Surface Photometry of the Giant Elliptical Galaxy NGC 4472 in the Virgo Cluster

Abstract

We present deep wide field (16'.4 x 16'.4) Washington CT1 CCD surface photometry of the giant elliptical galaxy NGC 4472, the brightest member in the Virgo cluster. Our data cover a wider field than any previous CCD photometry as well as going deeper. Surface brightness profiles of NGC 4472 are not well fit by a single King model, but they can be fit approximately by two King models: with separate models for the inner and outer regions. Surface brightness profiles for the outer region can also be fit approximately by a deVaucouleurs law. There is clearly a negative color gradient within 3' of NGC 4472, in the sense that the color gets bluer with increasing radius. The slope of the color gradient for this region is derived to be $Δμ(C-T_1)$ = -0.08 mag arcsec$^{-2}$ for $Δ\log r =1$, which corresponds to a metallicity gradient of $Δ$ [Fe/H] $= -0.2$ dex. However, the surface color gets redder slowly with increasing radius beyond 3'. A comparison of the structural parameters of NGC 4472 in C and T1 images has shown that there is little difference in the ellipse shapes between isochromes and isophotes. In addition, photometric and structural parameters of NGC 4472 have been determined.