Probing the distance and morphology of the Large Magellanic Cloud with RR Lyrae stars

Abstract

We present a Bayesian analysis of the distances to 15,040 Large Magellanic Cloud (LMC) RR Lyrae stars using V- and I-band light curves from the Optical Gravitational Lensing Experiment, in combination with new z-band observations from the Dark Energy Camera. Our median individual RR Lyrae distance statistical error is 1.89 kpc (fractional distance error of 3.76 per cent). We present three-dimensional contour plots of the number density of LMC RR Lyrae stars and measure a distance to the core LMC RR Lyrae centre of 50.2482±0.0546m̊(statistical)±0.4628(̊systematic)rk̊pc, equivalently μrmM̊C=18.5056±0.0024rm(åtistical)±0.02rm(st̊ematic). This finding is statistically consistent with and four times more precise than the canonical value determined by a recent meta-analysis of 233 separate LMC distance determinations. We also measure a maximum tilt angle of 11.84±0.80 at a position angle of 62, and report highly precise constraints on the V, I, and z RR Lyrae period–magnitude relations. The full dataset of observed mean-flux magnitudes, derived colour excess E(VI) values, and fitted distances for the 15,040 RR Lyrae stars produced through this work is made available through the publication's associated online data.

Publication
arXiv e-prints

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