The luminosity, the mass-metallicity dependence for RR Lyrae variables, and the luminosity of the clump stars in the bar of the LMC and their role in measuring distances are being investigated, in collaboration with Carretta and Gratton (Padova Obs.), and Marconi (Napoli Obs.).
B and V light curves have been obtained for 130 RR Lyraes, and 
S
metallicities have been derived for 6 double-mode (RRd) pulsators in the
sample (average metallicity: [Fe/H]=
). These metal abundances
coupled with mass determinations from pulsational models purposely computed
and the Petersen diagram are used to compare the mass-metallicity distribution
of field and cluster variables. Field and cluster RRd's are found to follow
the same mass-metallicity distribution, strengthening the case for uniformity
of properties between field and cluster variables (Bragaglia et al. 2001b).
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New BVI photometry in extremely good seeing and photometric conditions has been obtained for this project at the 1.5m Danish telescope in January 2001. The global pulsational properties of the sample as well as a very accurate estimate of the average apparent luminosity of the LMC RR Lyrae's and of the clump stars, have been obtained from the photometric data. An independent estimate of the LMC reddening was obtained from the colors of the edges of the instability strip defined by the RR Lyrae in our sample. Our findings have been compared to previous results in literature. In particular, we have done a straightforward comparison with OGLE photometry for the LMC clump stars, with fundamental bearings upon the short and long distance scale controversy (see Clementini et al. 2001a, astro-ph/0004771, M. Maio "Laurea" thesis, and Figure 5). The addition of the new data points has allowed a much improved refinement of the light curves and of the derived periods and epochs of the RR Lyrae variables (Di Fabrizio et al., in preparation).