Same as Fig. 2 but with three iso-metallicity curves from the theoretical model SONORA Elf Owl with parameters: log g = 5.0, log₁₀K_zz = 2, and solar C/O ratio in both diagrams. From left to right, the effective temperature of the model decreases from 1500 K to 300 K, with a step of 100 K, 50 K, and 25 K at the temperature above 1000 K, between 600–1000 K and below 600 K, respectively.