The Araucaria Project: The distance to the Carina Dwarf Galaxy from infrared photometry of RR Lyrae stars

TL;DR

This study uses near-infrared photometry of RR Lyrae stars to accurately determine the distance to the Carina Dwarf Galaxy, demonstrating the reliability of the NIR RR Lyrae method for distance measurements.

Contribution

It provides a new, precise distance measurement to the Carina Dwarf Galaxy using NIR RR Lyrae stars, confirming the method's effectiveness and consistency with other techniques.

Findings

Distance modulus of 20.118 mag with 0.017 (stat) and 0.11 (sys) mag uncertainty

NIR RR Lyrae method achieves 5% distance accuracy

Results agree with other independent distance estimates

Abstract

We obtained single-phase near-infrared (NIR) magnitudes in the $J$- and $K$-band for a sample of 33 RR Lyrae stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period-luminosity-metallicity relation for RR Lyrae stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 $\pm$ 0.017 (statistical) $\pm$ 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria Project from NIR photometry of Red Clump stars (20.165 $\pm$ 0.015) and Tip of Red Giant Branch (20.09 $\pm$ 0.03 $\pm$ 0.12 mag in $J$-band, 20.14 $\pm$ 0.04 $\pm$ 0.14 mag in $K$-band), as well as with most independent distance determinations to this galaxy. The near-infrared RR Lyrae method proved to be a reliable tool for accurate distance determination at the 5 percent level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids.