In the last years surface brightness profiles of a number of spiral galaxies have been published. Most of the data were obtained in the optical region (e.g., Courteau 1996; Héraudeau & Simien 1996 and references therein) but with the development of infrared arrays an increasing number of galaxies was measured in the infrared bands as well (e.g., Peletier et al. 1994; Héraudeau et al. 1996). Measurements of surface brightness profiles of galaxies are essential for quantitative investigations of galaxy morphology, decomposition of bulge and disc, studies of galaxy structure and stellar populations and measurements of dust distribution. Results from these studies give important information about the distribution of the luminous mass in a galaxy. Together with dynamical information (e.g., rotation curves) this leads to results about the dark matter distribution. Other important aspects are galaxy formation and evolution.
The surface brightness profile of a galaxy is produced by the spatial distribution of the stars as well as the spatial distribution of the dust. Since the amount of dust extinction in galaxies is still an unsolved problem, the surface brightness distributions of galaxies unaffected by dust are not clearly known. One way to obtain information about the dust content in a galaxy is to study surface brightness profiles in different wavelength bands ranging from the optical to the infrared region. Since the extinction of light in the infrared K-band is negligible, K-images of galaxies are used to determine the stellar distribution. Comparison with images obtained in the optical region gives information on the dust content of the galaxy. This approach has been used by various authors (e.g., Peletier et al. 1994; Block et al. 1994a,b). Byun et al. (1994) have shown from model calculations that the differences in dust extinction between the B- and I-bands are large enough for B-I colour profiles being a proper diagnostics for measuring the dust content of spiral galaxies.
A very important parameter for the stellar distribution within a spiral galaxy is the scalelength of the disc. However, scalelengths are also affected by the distribution of the dust. Measurements have shown that disc scalelengths of spiral galaxies tend to vary systematically with wavelength (see, e.g., Elmegreen & Elmegreen 1984; Peletier et al. 1994; Evans 1994). The shorter the wavelength, the larger is the disc scalelength. This means that significant colour gradients are present in discs of spirals. It is not clear yet to which extent these gradients are caused by gradients in the stellar population, by metallicity gradients or by dust extinction (Peletier et al. 1994; Evans 1994).
In this paper, profiles of surface brightness, apparent ellipticity and position angle in BVRI of a sample of 14 spiral galaxies are presented. For these galaxies, no BVRI surface brightness profiles have been published yet. All sample galaxies are found in the ESO-LV catalogue (Lauberts & Valentijn 1989). The profiles presented in this paper will be used to study the dust content of these galaxies in detail.
An exponential disc is fitted to each profile. The comparison of the scalelengths at different wavelengths shows a systematic decrease of disc scalelength with increasing wavelength for 13 of the 14 sample galaxies and confirms the presence of large colour gradients within galaxy discs.