Cepheid distances from infrared long-baseline interferometry

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Abstract
We report the angular diameter measurements of seven classical Cepheids, X Sgr, η Aql, W Sgr, ζ Gem, β Dor, Y Oph and Car that we have obtained with the VINCI instrument, installed at ESO's VLT Interferometer (VLTI). We also present reprocessed archive data obtained with the FLUOR/IOTA instrument on ζ Gem, in order to improve the phase coverage of our observations. We obtain average limb darkened angular diameter values of mas, mas, mas, mas, mas, mas, and mas. For four of these stars, η Aql, W Sgr, β Dor, and Car, we detect the pulsational variation of their angular diameter. This enables us to compute directly their distances, using a modified version of the Baade-Wesselink method: pc, pc, pc, pc. The stated error bars are statistical in nature. Applying a hybrid method, that makes use of the Gieren et al. ([CITE]) Period-Radius relation to estimate the linear diameters, we obtain the following distances (statistical and systematic error bars are mentioned): pc, pc, pc, pc, pc, pc, pc.