6.3 NIR Surface Brightness

The half-light "effective" radius and corresponding mean surface brightness are shown in Figures 21 and 22, respectively. Early-types are more compact (and consequently higher surface brightness) compared to late-type spirals (with the globular cluster an extreme example). With the Hubble type sequence, the trend is smooth from E to Sdm types. Although the "effective" aperture is better matched to the nuclear/bar regions, there are no appreciable differences between normal and barred spirals. If the "bar" fraction is in fact much higher than what has been previously tallied with optical photographs, then this null result may be due to the mixing of true "barred" galaxies within the normal galaxy sample. To avoid reddening and population/luminosity biases, a proper investigation of bars will require a predominantly infrared selected sample--the Atlas would be a good starting point.

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