5 Conclusions

We report on CCD BVI Johnson-Cousins photometry of stars in the fields of the southern stellar aggregates Ruprecht 103, 124, 129, 146 and 166, all of them included in open cluster catalogues (Alter et al. 1970; Lyngå 1987; Lauberts 1982). None of the observed (V, B-V) and (V, V-I) CMDs reveal the presence of an open cluster MS, except perhaps in the case of Ruprecht 166. The star sequences seen in the distinct CMDs, specially for Ruprecht 124 and Ruprecht 129, are apparently formed by the superimposition of MS field stars affected by varying amounts of interstellar absorption and/or placed at different distances from the Sun. The CMDs of Ruprecht 166 present a pronounced variation in the luminosity function along the apparent MS, a fact from which we can infer the notion that these stars had a different origin. We discuss the possible physical nature of the five studied objects by checking whether they present a significant number density contrast with respect to the Galactic field. Star counts performed within and outside the cluster candidate fields not only support the CMDs results but also suggest that the studied objects do not appear to be open cluster remnants.

Several other stellar aggregates included in open cluster catalogues have previously been disproved as genuine physical systems (see, e.g., Carraro & Patat 1995; Carraro 2000; Piatti & Clariá 2001). Thus, the present work implies the potential likelihood of other wrongly classified open clusters.

Acknowledgements

We have used DSS images for the analysis. The DSS was produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. We wish to thank the Director, staff and technicians of Las Campanas Observatory for the allocation of observing time and for their kind assistance and hospitality during the observing runs. We gratefully acknowledge financial support from the Argentinian institutions CONICET, SECYT (Universidad Nacional de Córdoba), and Agencia Córdoba Ciencia.