The VMC survey - XLIV: mapping metallicity trends in the large magellanic cloud using near-infrared passbands

We have derived high-spatial-resolution metallicity maps covering similar to 105 deg(2) across the Large Magellanic Cloud (LMC) using near-infrared passbands from the VISTA Survey of the Magellanic Clouds. We attempt to understand the metallicity distribution and gradients of the LMC up to a radius of similar to 6 kpc. We identify red giant branch (RGB) stars in spatially distinct Y, (Y - K-s) colour-magnitude diagrams. In any of our selected subregions, the RGB slope is used as an indicator of the average metallicity, based on calibration to metallicity using spectroscopic data. The mean LMC metallicity is [Fe/H] = -0.42 dex (sigma[Fe/H] = 0.04 dex). We find the bar to be mildly metal-rich compared with the outer disc, showing evidence of a shallow gradient in metallicity (-0.008 +/- 0.001 dex kpc(-1)) from the galaxy's centre to a radius of 6 kpc. Our results suggest that the LMC's stellar bar is chemically similar to the bars found in large spiral galaxies. The LMC's radial metallicity gradient is asymmetric. It is metal-poor and flatter towards the southwest, in the direction of the Bridge. This hints at mixing and/or distortion of the spatial metallicity distribution, presumably caused by tidal interactions between the Magellanic Clouds.

Automated summary

The study reveals that the metallicity of the Large Magellanic Cloud varies across different regions, with a higher metallicity in the center compared to the outer disc. The radial metallicity gradient shows asymmetry, being more metal-poor towards the southwest direction.