The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. IX. RR Lyrae Stars in the Small Magellanic Cloud

TL;DR

This paper presents a comprehensive catalog of 2475 RR Lyrae variable stars in the Small Magellanic Cloud from the OGLE-III survey, including their classifications, distributions, and statistical properties, with publicly available data.

Contribution

It provides the largest detailed catalog of RR Lyrae stars in the SMC, including classifications, period distributions, and spatial analysis, enhancing understanding of stellar populations in the galaxy.

Findings

SMC RR Lyrae stars have longer periods than LMC counterparts.

The mean periods for RRab, RRc, and RRe stars are 0.596, 0.366, and 0.293 days.

The spatial distribution shows a roughly round halo with two density maxima.

Abstract

The ninth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) comprises RR Lyr stars in the Small Magellanic Cloud (SMC). Our sample consists of 2475 variable stars, of which 1933 pulsate in the fundamental mode (RRab), 175 are the first overtone pulsators (RRc), 258 oscillate simultaneously in both modes (RRd) and 109 stars are suspected second-overtone pulsators (RRe). 30 objects are Galactic RR Lyr stars seen in the foreground of the SMC. We discuss some statistical features of the sample. Period distributions show distinct differences between SMC and LMC populations of RR Lyr variable stars, with the SMC stars having on average longer periods. The mean periods for RRab, RRc and RRe stars are 0.596, 0.366 and 0.293 days, respectively. The mean apparent magnitudes of RRab stars are equal to 19.70 mag in the V-band and 19.12 mag in the I-band. Spatial distribution of RR Lyr stars shows that the halo of the SMC is roughly round in the sky, however the density map reveals two maxima near the center of the SMC. For each object the multi-epoch V- and I-band photometry collected over 8 or 13 years of observations and finding charts are available to the astronomical community from the OGLE Internet archive.