STELLAR DISTRIBUTIONS AND NIR COLOURS OF NORMAL GALAXIES

We discuss some results of a morphological study of edge-on galaxies, based on op-tical and especially near-infrared surface photometry. We nd that the vertical surface brightness distributions of galaxies are tted very well by exponential proles, much bet-ter than by isothermal distributions. We nd that in general the vertical scale height increases when going outward. This increase is strong for early-type spiral galaxies and very small for late types. We argue that it can be due to the presence of thick discs with scale lengths larger than the galaxy’s main disc. Finally we discuss the colour-magnitude relation in I − K for spiral galaxies. We nd that it is a tight relation, for which the scatter is similar to the observational uncertainties, with a steeper slope than for elliptical galaxies.