New homogeneous iron abundances of double-mode Cepheids from high-resolution echelle spectroscopy*
Department of Optics & Quantum Electronics, University of Szeged, POB 406, Szeged 6701, Hungary e-mail: email@example.com
2 INAF - Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy
3 Konkoly Observatory of the Hungarian Academy of Sciences, POB 67, Budapest 1525, Hungary
Accepted: 18 June 2007
Aims.We define the relationship between the double-mode pulsation of Cepheids and metallicity in a more accurate way, determine the empirical metallicities of double-mode Cepheids from homogeneous, high-resolution spectroscopic data, and study of the period-ratio – metallicity dependence.
Methods. The high S/N echelle spectra obtained with the FEROS spectrograph were analyzed using a self-developed IRAF script, and the iron abundances were determined by comparing with synthetic spectra assuming LTE.
Results.Accurate [Fe/H] values of 17 galactic beat Cepheids were determined. All these stars have solar or slightly subsolar metallicity. Their period ratio () shows strong correlation with their derived [Fe/H] values. The corresponding period ratio – metallicity relation has been evaluated.
Key words: stars: variables: Cepheids / stars: atmospheres / stars: general
© ESO, 2007