The Araucaria Project. The Distance to the Sculptor dwarf spheroidal galaxy from infrared photometry of RR Lyrae stars

TL;DR

This study determines the distance to the Sculptor dwarf spheroidal galaxy using infrared photometry of RR Lyrae stars, achieving high precision and consistency with previous methods and calibrations.

Contribution

It provides a new, precise infrared-based distance measurement to Sculptor, validating multiple calibration methods and confirming previous optical and TRGB distances.

Findings

Distance modulus of 19.67 mag with small uncertainties

Infrared calibrations yield consistent distance results

Results agree with previous optical and TRGB measurements

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 $\pm$ 0.02 (statistical) $\pm$ 0.12 (systematic) mag for Sculptor from our data. This distance value is consistent with the value of 19.68 $\pm$ 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 (1993). It is also in a very good agreement with the results obtain by Rizzi (2002) based on tip of the red giant branch (TRGB, 19.64 $\pm$ 0.08 mag) and horizontal branch (HB, 19.66 $\pm$ 0.15 mag).