The Araucaria Project: The Distance to the Local Group Galaxy IC 1613 from Near‐Infrared Photometry of Cepheid Variables

We have measured accurate near-infrared magnitudes in the J and K bands of 39Cepheid variables in IC 1613 with well-determined periods and optical VI lightcurves. Using the template light curve approach of Soszy{\'n}ski, Gieren andPietrzy{\'n}ski, accurate mean magnitudes were obtained from these data whichallowed to determine the distance to IC 1613 relative to the LMC from amultiwavelength period-luminosity solution in the optical VI and near-IR JKbands, with an unprecedented accuracy. Our result for the IC 1613 distance is$(m-M)_{0} = 24.291 \pm 0.014$ (random error) mag, with an additionalsystematic uncertainty smaller than 2%. From our multiwavelength approach, wefind for the total (average) reddening to the IC 1613 Cepheids $E(B-V) = 0.090\pm 0.007$ mag,which is significantly higher than the foreground reddening ofabout 0.03 mag,showing the presence of appreciable dust extinction inside thegalaxy. Our data suggest that the extinction law in IC 1613 is very similar tothe galactic one.Our distance result agrees, within the uncertainties, with twoearlier infrared Cepheid studies in this galaxy of Macri et al. (from HST dataon 4 Cepheids), and McAlary et al. (from ground-based H-band photometry of 10Cepheids), but our result has reduced the total uncertainty on the distance toIC 1613 (relative to the LMC) to less than 3%. With distances to nearbygalaxies from Cepheid infrared photometry at this level of accuracy, which arecurrently being obtained in our Araucaria Project, it seems possible tosignificantly reduce the systematic uncertainty of the Hubble constant asderived from the HST Key Project approach, by improving the calibration of themetallicity effect on PL relation zero points, and by improving the distancedetermination to the LMC.Comment: ApJ in pres