Photometric metallicity map of the Small Magellanic Cloud

الأصل · EN

We have created an estimated metallicity map of the Small Magellanic Cloud (SMC) 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 2.5∘. 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 available spectroscopic data for selected subregions. The average metallicity of the SMC is found to be [Fe/H] = -0.94 dex (σ[Fe/H] = 0.09) from OGLE III, and [Fe/H] = -0.95 dex (σ[Fe/H] = 0.08) from MCPS. We confirm a shallow but significant metallicity gradient within the inner SMC up to a radius of 2.5∘ (-0.045±0.004 dex deg⁻¹ to -0.067±0.006 dex deg⁻¹).