The araucaria project: The distance to the sculptor dwarf spheroidal galaxy from infrared photometry of RR lyrae stars

Abstract

We have obtained single-phase near-infrared magnitudes in the J and K bands for a sample of 78 RR Lyrae stars in the Sculptor dSph galaxy. Applying different theoretical and empirical calibrations of the period-luminosity- metallicity relation for RR Lyrae stars in the infrared, we find consistent results and obtain a true, reddening-corrected distance modulus of 19.67 0.02 (statistical) 0.12 (systematic) mag for Sculptor from our data. This distance value is consistent with the value of 19.68 0.08 mag which we obtain from earlier V-band data of RR Lyrae stars in Sculptor, and the V magnitude metallicity calibration of Sandage. It is also in very good agreement with the results obtained by Rizzi based on the tip of the red giant branch (TRGB, 19.64 0.08 mag) and horizontal branch (HB, 19.66 0.15 mag). © 2008. The American Astronomical Society. All rights reserved.