Cepheid distances from infrared long-baseline interferometry

II. Calibration of the period–radius and period–luminosity relations

¹ LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France e-mail: pierre.kervella@obspm.fr
² European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago 19, Chile
³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁴ Observatoire de la Côte d'Azur, Département GEMINI, UMR 6203, BP 4229, 06304 Nice Cedex 4, France

Received: 29 October 2003
Accepted: 4 May 2004

Abstract

Using our interferometric angular diameter measurements of seven classical Cepheids reported in Kervella et al. ([CITE], A&A, 416, 941 – Paper I), complemented by previously existing measurements, we derive new calibrations of the Cepheid period–radius (P–R) and period–luminosity (P–L) relations. We obtain a P–R relation of , only 1 σ away from the relation obtained by Gieren et al. ([CITE], ApJ, 496, 17). We therefore confirm their P–R relation at a level of . We also derive an original calibration of the P–L relation, assuming the slopes derived by Gieren et al. ([CITE]) from LMC Cepheids, and . With a P–L relation of the form , we obtain reference points of and . Our calibration in the V band is statistically identical to the geometrical result of Lanoix et al. ([CITE], MNRAS, 308, 969).