6.1 NIR Radial Color Distribution

The near-infrared radial J-Ks color distribution for the entire set of Atlas galaxies is shown in Figure 19 (for the analogous single galaxy plot of NGC 253, see Figure 7). The upper panel shows normal galaxies and the lower panel barred galaxies. In order to combine galaxies of different sizes, the radius is normalized by the J-band half-light radius. All Hubble types show the general trend of red nuclear light (J-Ks > 1) and blue disk or bulge light (J-Ks < 0.9), probably indicative of nuclear reddening (late types), older stellar populations, and low metallicity. The E/S0 types seem to show the smoothest distributions (no doubt due to the lack of dust extinction), while Sc/Sd late-types show the flattest "disk" distributions (probably due to the lack of bulges or spheroidal light). The "barred" galaxies have radial color distributions that show large scatter, probably due to their asymmetric light distributions and small number statistics ("SB" bars represent a small fraction of the sample). Still it is interesting to note that barred galaxies have much redder nuclei, J-K > 1.1, hinting at the greater activity (starburst and AGN) that might be associated with bars (see also, NGC 253, Figures 6-7).

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