2004A&A...423..327K

Using our interferometric angular diameter measurements of seven classical Cepheids reported in Kervella et al. (2004A&A...416..941K), 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 logR=[0.767±0.009]logP+[1.091±0.011], only 1σ away from the relation obtained by Gieren et al. (1998ApJ...496...17G). We therefore confirm their P-R relation at a level of Δ(logR)=±0.02. We also derive an original calibration of the P-L relation, assuming the slopes derived by Gieren et al. (1998ApJ...496...17G) from LMC Cepheids, α_K=-3.267±0.042 and α_V=-2.769±0.073. With a P-L relation of the form M_λ=α_λ(logP-1)+β_λ, we obtain logP=1 reference points of β_K=-5.904±0.063 and β_V=-4.209±0.075. Our calibration in the V band is statistically identical to the geometrical result of Lanoix et al. (1999MNRAS.308..969L).