Near-Infrared Observations of RR Lyrae Variables in $ω$ Centauri

Abstract

We present Near-Infrared (NIR) $J$ and $K_s$-band observations for 181 RR Lyrae stars in the Galactic Globular Cluster $ω$ Cen. The comparison between predicted and empirical slopes of NIR Period-Luminosity (PL) relations indicates a very good agreement. Cluster distance estimates based on NIR PL relations agree quite well with recent determinations based on different standard candles, giving a true mean distance modulus $μ= 13.71\pm0.05$, and $d=5.52\pm0.13$ kpc.

2 pages, 1 figure, to appear in the proceedings of the Workshop "Stellar Pulsation and Evolution", 2005. Monte Porzio Catone, Italy. Eds.: A.R. Walker and G. Bono