Abstract:
We have estimated a metallicity map of the Large Magellanic Cloud (LMC) using the Mag-
ellanic 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
◦
, 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 in-
dicator 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 (
σ
[Fe/H]
=
0.12) from MCPS
data, and [Fe/H]
=−
0.39 dex (
σ
[Fe/H]
=
0.10) from OGLE III data. The bar is found to 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
±
0.002 dex kpc
−
1
to
−
0.066
±
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.
