The VMC survey - XXVI. Structure of the Small Magellanic Cloud from RR Lyrae stars

Abstract

We present results from the analysis of 2997 fundamental mode RR Lyrae variables located in the Small Magellanic Cloud (SMC). For these objects near-infrared time-series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and visual light curves from the OGLE IV survey are available. In this study the multi-epoch $K_{\mathrm{s}}$-band VMC photometry was used for the first time to derive intensity-averaged magnitudes of the SMC RR Lyrae stars. We determined individual distances to the RR Lyrae stars from the near-infrared period-absolute magnitude-metallicity ($P{M}_{K_{\mathrm{s}}}Z$) relation, which has a number of advantages in comparison with the visual absolute magnitude-metallicity ($M_V-[Fe/H]$) relation, such as a smaller dependence of the luminosity on interstellar extinction, evolutionary effects and metallicity. The distances we have obtained were used to study the three-dimensional structure of the SMC. The distribution of the SMC RR Lyrae stars is found to be ellipsoidal. The actual line-of-sight depth of the SMC is in the range from 1 to 10 kpc, with an average depth of 4.3 $\pm$ 1.0 kpc. We found that RR Lyrae stars in the eastern part of the SMC are affected by interactions of the Magellanic Clouds. However, we do not see a clear bimodality in the distribution of RR Lyrae stars as observed for red clump (RC) stars.

18 pages, 15 figures, 3 tables. Accepted for publication in MNRAS

References in corpus (17)

• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The VISTA Science Archive
• New Optical Reddening Maps of the Large and Small Magellanic Clouds
• Clustering of Local Group distances: publication bias or correlated measurements? III. The Small Magellanic Cloud
• The VMC Survey - XIV. First results on the look-back time star-formation rate tomography of the Small Magellanic Cloud
• The VMC Survey. XXV. The 3D structure of the Small Magellanic Cloud from Classical Cepheids
• Clouds, Streams and Bridges. Redrawing the blueprint of the Magellanic System with Gaia DR1
• The RR Lyrae Period - K Luminosity relation for Globular Clusters: an observational approach
• Gaia Data Release 1 - The Cepheid & RR Lyrae star pipeline and its application to the south ecliptic pole region
• New near-infrared period-luminosity-metallicity relations for RR Lyrae stars and the outlook for Gaia
• The VMC Survey. XIII. Type II Cepheids in the Large Magellanic Cloud
• The infrared JHK light curves of RR Lyr
• The VMC survey - XXIII. Model fitting of light and radial velocity curves of Small Magellanic Cloud classical Cepheids
• Eclipsing binary stars in the Large Magellanic Cloud. Results from the EROS-2, OGLE and VMC surveys
• Morphology and metallicity of the Small Magellanic Cloud using RRab stars
• RR Lyrae variables in the Small Magellanic Cloud - II. The extended area: chemical and structural analysis

Cited by in corpus (4)

• Standard Galactic Field RR Lyrae II: A Gaia DR2 calibration of the period-Wesenheit-metallicity relation
• The VMC Survey -- XXXV. Model fitting of LMC Cepheid light curves
• The intrinsic reddening of the Magellanic Clouds as traced by background galaxies -- II. The Small Magellanic Cloud
• Distance, reddening and three dimensional structure of the SMC - I: Using RRab stars