Behavior of the iron abundances as a function of the excitation potential, χ, for the AGB star #25, in the case of the photometric T_eff adopted by C17 (upper panel) and of the spectroscopic T_eff derived by L16 (lower panel). The black circles are for the abundances derived from neutral Fe lines and the red circles are for the single ionized Fe lines. The blue lines are the best linear fits obtained to the Fe I abundances.