The Araucaria Project. The Distance to the Small Magellanic Cloud from Near-Infrared Photometry of RR Lyrae Variables

TL;DR

This study uses near-infrared observations of RR Lyrae stars to precisely measure the distance to the Small Magellanic Cloud, confirming previous estimates and refining the galaxy's distance measurement.

Contribution

It provides a new, accurate distance measurement to the SMC using infrared RR Lyrae observations and compares it with previous methods.

Findings

SMC distance modulus of 18.97 mag with high precision.

Consistent results across different calibrations.

SMC is 0.39 mag farther than the LMC.

Abstract

We have obtained deep infrared J and K band observations of nine 4.9x4.9 arcmin fields in the Small Magellanic Cloud (SMC) with the ESO New Technology Telescope equipped with the SOFI infrared camera. In these fields, 34 RR Lyrae stars catalogued by the OGLE collaboration were identified. Using different theoretical and empirical calibrations of the infrared period-luminosity-metallicity relation, we find consistent SMC distance moduli, and find a best true distance modulus to the SMC of 18.97 +/- 0.03 (statistical) +/- 0.12 (systematic) mag which agrees well with most independent distance determinations to this galaxy, and puts the SMC 0.39 mag more distant than the LMC for which our group has recently derived, from the same technique, a distance of 18.58 mag.