Upper panel: schematic view of the G2 star with a dark spot rotating across the projected stellar disk. The color code indicates the intensity across the disk. Middle panel: RV curve produced by the flux effect of a dark spot. Lower panel: RV curve produced by the flux effect of a bright plage. The stellar effective temperature in this models is T_eff = 5780 K. The spot is 550 K cooler than the quiet stellar photosphere and the plage temperature is derived from Eq. (1).