Individual and combined contributions of Mg isotopes to region 1 of HD 18907. The top left panel shows the synthetic spectral feature from ²⁴Mg only (no contribution from ²⁵Mg or ²⁶Mg). The top right panel shows the feature from ²⁵Mg only, and the bottom left panel shows the ²⁶Mg contribution. The bottom right panel with the fitting region in the blue box, presents the combined synthetic spectrum including all three isotopes, providing the best fit solution for this region.