Emergent half-line Mg II k profiles. The first three columns show isothermal isobaric models; the last three columns show PCTR models with γ = 2. Each panel is colour-coded to show a different temperature: 6000 K (purple), 8000 K (dark blue), 10 000 K (light blue), 15 000 K (teal), 20 000 K (green), 25 000 K (lime green), 30 000 K (yellow), 35 000 K (orange), and 40 000 K (red). Intensities generally increase for higher pressure and slab thickness.