Top panel: influence of spot temperature on spot RVs of the F3 star. Calculations done with ΔT = 550 K (blue short dashed line), ΔT = 1100 K (green long dashed), and ΔT = 2553 K chosen according to the spectral type (black solid line). Lower panel: fractional symmetry parameter as a function of spot contrast for spectral types F3 (blue), G2 (green) and K5 (red). The gray crosses mark the contrasts of the spot temperatures derived from Fig. 12 for the F3, G2, and K5 stars, and the cyan “x” symbols mark the contrasts associated to a spot temperature contrast of 550K used in the earlier sections.