We present new empirical and theoretical calibrations of two photometric metallicity indices based on Walraven photometry. The empirical calibration relies on a sample of 48 Cepheids for which iron abundances based on high resolution spectra are available in the literature. They cover a broad range in metal abundance (-0.5 < [Fe/H] < +0.5) and the intrinsic accuracy of the Metallicity Index Color (MIC) relations is better than 0.2 dex. The theoretical calibration relies on a homogeneous set of scaled-solar evolutionary tracks for intermediate-mass stars and on pulsation predictions concerning the topology of the instability strip. The metal content of the adopted evolutionary tracks ranges from Z=0.001 to Z=0.03 and the intrinsic accuracy of the MIC relations is better than 0.1 dex.
@article{arxiv.0712.3006,
title = {Metallicity estimates of Galactic Cepheids based on Walraven photometry},
author = {S. Pedicelli and J. Lub and J. W. Pel and B. Lemasle and G. Bono and P. Francois and D. Laney and A. Piersimoni and F. Primas and M. Romaniello and R. Buonanno and F. Caputo and S. Cassisi and F. Castelli and A. Pietrinferni and J. Pritchard},
journal= {arXiv preprint arXiv:0712.3006},
year = {2007}
}
Comments
6 pages, 5 figures; to appear in Mem. Soc. Astr. Italiana, Vol. 79/2 (proceeding Cefalu' Workshop "XXI Century Challenges for Stellar Evolution", ed. S. Cassisi & M. Salaris)