Iron abundances of southern double-mode cepheids from high-resolution echelle spectroscopy

We determined [Fe/H] for 17 double-mode Cepheids of the southern hemisphere using high-resolution echelle spectra. For five of the program stars these are the first iron abundances in the literature. The available data suggest that the period ratio for galactic beat Cepheids is mainly determined by their metallicity. Therefore, the observed period ratios do not reflect large differences in their mass, effective temperature or luminosity.