Multicolor photometric properties of six early-type galaxies

Abstract

We present BV RI CCD surface photometry for 4 elliptical and 2 S0 galaxies that show bright emission lines in their nuclear spectra. We obtained isophote maps, luminosity profiles, and basic photometric parameters. We also obtained continuum subtracted Hα +[NII] images for 5 galaxies in our sample, but only in two of them, NGC 6858 and ESO 185-54, we detected emission gas. We used the standard technique of ellipse fitting to determine the radial variation of surface brightness, color, ellipticity, position angle and the fourth order Fourier coefficient of the deviations from elliptical shape to look for isophotal twists, color gradients and fine structure variations. We have fitted an r1=n S´ersic law to the light profiles, finding that it provides a better fit to the light profiles of the ellipticals than the traditional r1/4 law. However, this lawdoes not provide a good fit for SO galaxies.