M. Romaniello, F. Primas, M. Mottini, M. Groenewegen, G. Bono, P. Francois
Published 2004-11-22, updated 2004-11-23Version 2
We have assessed the influence of the stellar iron content on the Cepheid Period-Luminosity (PL) relation by relating the V band residuals from the Freedman et al (2001) PL relation to [Fe/H] for 37 Galactic and Magellanic Clouds Cepheids. The iron abundances were measured from FEROS and UVES high-resolution and high-signal to noise optical spectra. Our data indicate that the stars become fainter as metallicity increases, until a plateau or turnover point is reached at about solar metallicity. Our data are incompatible with both no dependence of the PL relation on iron abundance, and with the linearly decreasing behavior often found in the literature (e.g. Kennicutt et al 1998, Sakai et al 2004). On the other hand, non-linear theoretical models of Fiorentino et al (2002) provide a fairly good description of the data.
Comments: 5 pages, 2 figures. Accepted for pubblication in Astronomy & Astrophysics Letters (Table 1 will only appear in electronic form). Revised version (23.11.04) to fix typo in Table 1 (the V magnitudes for Galactic stars were wrong)
Journal: Astron.Astrophys. 429 (2005) L37
Determining the Metallicity of Cepheid Stars in the SMC, LMC and the Galaxy
Fe Kαemission from photoionized slabs: the impact of the iron abundance
Chemical Composition of Two H II Regions in NGC 6822 Based on VLT Spectroscopy
