Elemental abundances as a function of condensation temperature for the stars in the sample by Meléndez et al. (2009, M09). Left panels: crosses are the [X/Fe] versus T_C relations for 11 solar twin stars according to M09. Solid lines are linear fits to the data. Right panels: as in the left panels, but for Δ [X/Fe], where the chemical abundance reference is not the Sun, but the average of the two least refractory-element-depleted (“pristine”) solar twins.