The VMC survey – XXXI: The spatially resolved star formation history of the main body of the Small Magellanic Cloud

Abstract

We recover the spatially resolved star formation history across the entire\nmain body and Wing of the Small Magellanic Cloud (SMC), using fourteen deep\ntile images from the VISTA survey of the Magellanic Clouds (VMC), in the YJKs\nfilters. The analysis is performed on 168 subregions of size 0.143 deg2,\ncovering a total contiguous area of 23.57 deg2. We apply a colour-magnitude\ndiagram (CMD) reconstruction method that returns the best-fitting star\nformation rate SFR(t), age--metallicity relation, distance and mean reddening,\ntogether with their confidence intervals, for each subregion. With respect to\nprevious analyses, we use a far larger set of VMC data, updated stellar models,\nand fit the two available CMDs (Y-Ks versus Ks and J-Ks versus Ks)\nindependently. The results allow us to derive a more complete and more reliable\npicture of how the mean distances, extinction values, star formation rate, and\nmetallicities vary across the SMC, and provide a better description of the\npopulations that form its Bar and Wing. We conclude that the SMC has formed a\ntotal mass of (5.31+-0.05)x10^8 Msun in stars over its lifetime. About two\nthirds of this mass is expected to be still locked in stars and stellar\nremnants. 50 per cent of the mass was formed prior to an age of 6.3 Gyr, and 80\nper cent was formed between 8 and 3.5 Gyr ago. We also illustrate the likely\ndistribution of stellar ages and metallicities in different parts of the CMD,\nto aid the interpretation of data from future astrometric and spectroscopic\nsurveys of the SMC.\n