Emission line velocity, metallicity, and extinction maps of the Small Magellanic Cloud

Optical emission lines across the Small Magellanic Cloud (SMC) have been measured from multiple fields using the Australian National University 2.3m telescope with the wide-field spectrograph. Interpolated maps of the gas-phase metallicity, extinction, H αradial velocity, and H αvelocity dispersion have been made from these measurements. There is a metallicity gradient from the centre to the north of the galaxy of ∼-0.095 dex kpc -1 with a shallower metallicity gradient from the centre to the south of the galaxy of ∼-0.013 dex kpc -1 . There is an extinction gradient of ∼-0.086 E ( B -V)/kpc from the centre going north and shallower going from the centre to the south of ∼-0.0089 E ( B -V )/kpc. The SMC eastern arm has lower extinction than the main body. The radial velocity of the gas from the H αline and the H I line have been compared across the SMC. In general there is good agreement between the two measurements, though there are a few notable exceptions. Both show a region that has different radial velocity to the bulk motion of the SMC in the southern western corner by at least 16 km s -1 . The velocity dispersion from H αand H I across the SMC have also been compared, with the H αvelocity dispersion usually the higher of the two. The eastern arm of the SMC generally has lower velocity dispersion than the SMC's main body. These measurements enable a detailed examination of the SMC, highlighting its nature as a disrupted satellite galaxy.