A&A 429, L37-L40 (2005)
DOI: 10.1051/0004-6361:200400110

Letter

The influence of chemical composition on the properties of Cepheid stars

I. Period-Luminosity relation vs. iron abundance

M. Romaniello¹, F. Primas¹, M. Mottini¹, M. Groenewegen², G. Bono³ and P. François<sup>4

1</sup>  European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
    e-mail: mromanie@eso.org
²  Instituut voor Sterrenkunde, PACS - ICC, Celestijnenlaan 200B, 3001 Leuven, Belgium
³  INAF - Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
⁴  Observatoire de Paris-Meudon, GEPI, 61 avenue de l'Observatoire, 75014 Paris, France

(Received 11 October 2004 / Accepted 20 November 2004)

Abstract
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.

Key words: stars: abundances -- stars: distances -- Cepheids

SIMBAD Objects

© ESO 2004

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

• If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
• You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
• You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.