Effect of eccentricity on the RV semi-amplitude K of the RG component. The x-axis is the orbital period P_orb expressed in days, which runs from 0.1 day to ≈274 years. The y-axis is the orbital eccentricity. Systems are assumed to have a mass ratio (q = 0.8) with M₁ = 1.2 M_⊙, and to be seen edge-on (i = 90°). The area delimited by dashed lines indicates the range of values met for systems in which surface activity is measured.