7 Conclusion

The bulge shape of a large sample of edge-on galaxies was investigated using DSS, CCD images in the optical wavelengths regime and in the NIR. Our main conclusions are:

• We have presented a visual classification of bulges in three b/p types and one elliptical type;

• 45% of all disk galaxies (S0 - Sd) have a b/p bulge. This fraction is based on a sample of 734 galaxies;

• For the first time a large fraction (40%) of b/p bulges in Sd galaxies is found;

• Comparisons between the fraction of barred galaxies and galaxies with b/p bulges show that b/p bulges can be explained by evolution scenarios based on bars;

• NIR observations reveal that dust is not responsible for the shape of b/p bulges;

• The shape of bulges is constant over a large region of wavelengths (350 nm - 2.2 $\mu$m).

Acknowledgements

Part of this work was supported by the Deutsche Forschungsgemeinschaft, DFG. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. It also uses the Digitized Sky Survey (DSS) based on photographic data obtained using Oschin Schmidt Telescope on Palomar Mountain and The UK Schmidt Telescope and produced at the Space Telescope Science Institute.