Abstract :

We present results from an analysis of ∼29 000 RR Lyrae stars located in the Large Magellanic Cloud (LMC). For these objects, near-infrared time-series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and optical data from the OGLE (Optical Gravitational Lensing Experiment) IV survey and the Gaia Data Release 2 catalogue of confirmed RR Lyrae stars were exploited. Using VMC and OGLE IV magnitudes we derived period-luminosity (PL), period-luminosity-metallicity (PLZ), period-Wesenheit (PW) and period-Wesenheit-metallicity (PWZ) relations in all available bands. More that 7000 RR Lyrae were discarded from the analysis because they appear to be overluminous with respect to the PL relations. The PLKsPLKs relation was used to derive individual distance to ∼22 000 RR Lyrae stars, and study the three-dimensional structure of the LMC. The distribution of the LMC RR Lyrae stars is ellipsoidal with the three axis S₁=6.5 kpc, S₂=4.6 kpc and S₃=3.7 kpc, inclination i=22 ± 4° relative to the plane of the sky and position angle of the line of nodes θ = 167 ± 7° (measured from north to east). The north-eastern part of the ellipsoid is closer to us and no particular associated substructures are detected as well as any metallicity gradient.

Publication : Monthly Notices of the Royal Astronomical Society, Advance Access
DOI : 10.1093/mnras/stab901 
Bibcode : 2021MNRAS.tmp..900C 
Keywords : Stars: variables: RR Lyrae; galaxies: Magellanic Clouds; galaxies: distances and redshifts; surveys; Astrophysics - Astrophysics of Galaxies