Radiative opacity as a function of the density parameter $\tilde{R}$ (with density shown on the upper x-axis) from the AESOPUS2.1 tables. For comparison, the Freedman opacity curves as implemented in MESA are shown in light shades. The three panels, from left to right, correspond to temperatures of log T [K]= 2, 3, and 3.6. The blue, red, and yellow lines represent metallicities of Z = 0.80, 0.20, and 0.02, respectively. Solid lines indicate regions with tabulated data points (log($\tilde{R}$/(g/cm³)) ≤ 6), dotted lines show linear extrapolation on logarithmic values (see eq. A.1), and dashed lines denote constant values outside the data region.