# Pulsating stars in $\omega$ Centauri: Near-IR properties and period-luminosity relations

## TL;DR

This study presents a comprehensive near-infrared variability survey of $ ext{ω}$ Centauri, analyzing pulsating stars and their period-luminosity relations to improve understanding of their properties and detection methods.

## Contribution

It provides the first homogeneous near-IR catalog of variable stars in $ ext{ω}$ Centauri and explores their light curves and period-luminosity relations across different pulsating star types.

## Key findings

- Near-IR observations reveal differences in light curves compared to optical data.
- Small amplitudes of SX Phoenicis stars in near-IR affect detection capabilities.
- A unified period-luminosity relation may describe all pulsating stars in the cluster.

## Abstract

$\omega$ Centauri (NGC~5139) contains many variable stars of different types, including the pulsating type II Cepheids, RR Lyrae and SX Phoenicis stars. We carried out a deep, wide-field, near-infrared (IR) variability survey of $\omega$ Cen, using the VISTA telescope. We assembled an unprecedented homogeneous and complete $J$ and $K_{\rm S}$ near-IR catalog of variable stars in the field of $\omega$ Cen. In this paper we compare optical and near-IR light curves of RR Lyrae stars, emphasizing the main differences. Moreover, we discuss the ability of near-IR observations to detect SX Phoenicis stars given the fact that the amplitudes are much smaller in these bands compared to the optical. Finally, we consider the case in which all the pulsating stars in the three different variability types follow a single period-luminosity relation in the near-IR bands.