6 Summary

Radial velocities of 94 objects in central fields of the Fornax cluster have been measured with low resolution spectroscopy. Our spectroscopic sample is limited in absolute magnitude at about V = 20.0 mag and in peak surface brightness at about $\mu_{\rm peak} = 22.5$ mag arcsec^-2. Most of the velocity determinations of the fainter galaxies are based on strong emission lines of late type galaxies.

Eight objects were identified as Fornax members due to their radial velocities. Five of them are listed as nucleated dwarf ellipticals in the FCC. With one exception the membership and/or background classification by Ferguson (1989), which is based on galaxy morphology, agrees very well with our results. Among the three "new'' Fornax members, there are two that have photometric properties that can be explained by a very bright GC as well as by a compact elliptical like M 32. Another explanation might be that these objects represent the nuclei of dissolved dE, Ns. The measurement of line indices has shown that the brighter one of these objects has a solar metallicity, whereas the other nucleus-like object as well as the nuclei of the measured dE, Ns have line indices that are similar to those of old metal-poor GCs. It would be interesting to investigate, whether there are more objects of this kind hidden among the high surface brightness objects in the central Fornax cluster.

Among the background galaxies we found a concentration of galaxies with velocities around $v_{\rm helio} =$ 33700 km s^-1. These 19 galaxies are spatially concentrated near the central Fornax galaxy NGC 1399 as well. Their velocity dispersion, $\sigma_v = 316$ km s^-1, is typical for a relatively poor galaxy cluster. The brightest member galaxy, located $1\hbox{$.\mkern-4mu^\prime$}1$ south of NGC 1399, has a similar absolute magnitude and extended cD profile as NGC 1399. We estimated that all excess galaxies in the central Fornax fields, except the known and "new'' Fornax members, most probably belong to the background cluster just behind the Fornax center.

Acknowledgements

We thank Harald Kuntschner for providing us an electronic version of his data on elliptical galaxies in Fornax. We also thank the referee H.C. Ferguson for his useful comments which improved the paper. This research was partly supported by the DFG through the Graduiertenkolleg "The Magellanic System and other dwarf galaxies" and through grant Ri 418/5-1 and Ri 418/5-2. LI thanks Fondecyt Chile for support through "Proyeto FONDECyT 8970009".