We have estimated a metallicity map of the Large Magellanic Cloud ( LMC ) using the Magellanic Cloud Photometric Survey ( MCPS ) and Optical Gravitational Lensing Experiment ( OGLE III ) photometric data .
This is a first of its kind map of metallicity up to a radius of 4 - 5 degrees , derived using photometric data and calibrated using spectroscopic data of Red Giant Branch ( RGB ) stars .
We identify the RGB in the V , ( V - I ) colour magnitude diagrams of small subregions of varying sizes in both data sets .
We use the slope of the RGB as an indicator of the average metallicity of a subregion , and calibrate the RGB slope to metallicity using spectroscopic data for field and cluster red giants in selected subregions .
The average metallicity of the LMC is found to be [ Fe/H ] = - 0.37 dex ( \sigma [ Fe/H ] = 0.12 ) from MCPS data , and [ Fe/H ] = - 0.39 dex ( \sigma [ Fe/H ] = 0.10 ) from OGLE III data .
The bar is found be the most metal-rich region of the LMC .
Both the data sets suggest a shallow radial metallicity gradient up to a radius of 4 kpc ( - 0.049 \pm 0.002 dex kpc ^ { -1 } to - 0.066 \pm 0.006 dex kpc ^ { -1 } ) .
Subregions in which the mean metallicity differs from the surrounding areas do not appear to correlate with previously known features ; spectroscopic studies are required in order to assess their physical significance .