Fitted MBBV emissivity index β plotted against fitted dust temperature T_dust. The left panel shows the MBBV fits to the data, and the right the MBBV fits to the best-fit DL07 models. Data are distinguished by O/H with (red) circles showing 12 + log (O/H)>8.4, (green) triangles 8.0 <12 + log (O/H)≤ 8.4, and (blue) squares 12 + log (O/H)≤ 8.1. Filled symbols correspond to positions with normalized (to optical radius R_opt) radii within R/R_opt≤ 0.8, and open symbols to larger radii.