SIMBAD references

We use the results from recent computations of updated non-linear convective pulsating models to constrain the distance modulus of Galactic globular clusters through the observed periods of first-overtone (RR_c) pulsators. The resulting relation between the mean absolute magnitude of RR Lyrae stars <]M_V(RR)> and the heavy element content [Fe/H] appears well in the range of several previous empirical calibrations, but with a non-linear dependence on [Fe/H] so that the slope of the relation increases when moving towards larger metallicities. On this ground, our results suggest that metal-poor ([Fe/H]←1.5) and metal-rich ([Fe/H]>-1.5) variables follow two different linear <]M_V(RR)>-[Fe/H] relations. Application to RR Lyrae stars in the metal-poor globular clusters of the Large Magellanic Cloud (LMC) provides an LMC distance modulus of the order of 18.6mag, thus supporting the `long' distance scale. The comparison with recent predictions based on updated stellar evolution theory is briefly presented and discussed.