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Up: Star clusters in the vdB-Hagen 99


6 Conclusions

In this paper we presented UBVRI CCD photometry for three young clusters in the direction of the Carina spiral feature: NGC 3114, Collinder 228 and vdB-Hagen 99. Our results can be summarized as follows:

$\bullet$ NGC 3114 lies in the outskirts of the Carina nebula, at a distance of 920 pc from the Sun. In the field we studied, we isolate 7 cluster members, which has a low reddening ( $E(B-V)=0.07\pm 0.03$) and a maximum age of $3 \times 10^{8}$ yrs.
$\bullet$ Collinder 228 is a younger ( $8\times 10^{6}$) yrs cluster located in front of the Carina nebula complex. We identify 11 new candidate members and confirm that 30% of the cluster members are probably unresolved binaries.
$\bullet$ Finally, vdB-Hagen 99 is a loose open cluster about 108 yrs old, and with a fairly low mean reddening. We confirm previous results, and add 4 new members.

Putting together the results of this paper and those of previous works (Patat & Carraro 2001; Carraro et al. 2001), the Carina complex turns out to be populated by very young clusters (like Collinder 228, NGC 3324 and Bochum 11) in its inner region, and by young or intermediate age objects (like NGC 3114, vdB-Hagen 99 and Loden 165) in its outskirts.

This confirms previous suggestions by Feinstein (1995) about the existence of an age gradient in the Carina complex. We shall discuss this issue in more details in forthcoming papers, when all the clusters observed in our survey will be analysed.

Acknowledgements
G.C. acknowledges kind hospitality from ESO. This study made use of Simbad and WEBDA. The suggestions of an anonymous referee are warmly acknowledged.


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