2024MNRAS.535.2598L

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 $\alpha$ radial velocity, and H $\alpha$ velocity dispersion have been made from these measurements. There is a metallicity gradient from the centre to the north of the galaxy of $\sim$-0.095 dex kpc^–1 with a shallower metallicity gradient from the centre to the south of the galaxy of $\sim$-0.013 dex kpc^–1. There is an extinction gradient of $\sim$-0.086 E(B - V)/kpc from the centre going north and shallower going from the centre to the south of $\sim$-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 $\alpha$ line 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 $\alpha$ and H I across the SMC have also been compared, with the H $\alpha$ velocity 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.