Variable stars in nearby galaxies

VII. P-L relation in the BVRI bands of Cepheids in IC 1613

¹ INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy e-mail: elio@merate.mi.astro.it
² Grupo de Astronomia, Departamento de Fisica, Universidad de Concepción, Casilla 160-C, Concepción, Chile e-mail: wgieren@astro-udec.cl

Received: 13 July 2005
Accepted: 12 September 2005

Abstract

A set of six BVRI observations collected with the WFI at the ESO 2.2 m telescope have been used to derive multicolor data of Cepheids in IC 1613 identified in previous surveys. Since part of the previously known data were obtained only in VI filters or without filter (Wh) bands, the method of Freedman has been applied to get reliable mean intensity values of Cepheid magnitudes in the various bands. The resulting slopes of the relations in the BVI bands are similar, within the uncertainties, to those previously obtained by other authors for the LMC. The distribution of the Cepheids in the period–color diagrams is compatible with a change near  d as observed in LMC. The distribution in the color–color diagrams is more similar to that in SMC, and this should be related to the very low metallicity of the galaxy.