K-G-F dwarfs stellar granulation variability

Although we do not observe a significant effect of age or cyclic activity, stars with a higher metallicity tend to have a lower convective blueshift, with a larger effect than expected from numerical simulations. Finally, we estimate that for 71% of the stars in our sample the RV and LogR'_HK_ variations are compatible with the effect of activity on convection, as observed in the solar case, while for the other stars, other sources (such as binarity or companions) must be invoked to explain the large RV variations.

We also confirm a relationship between LogR'_HK_ and metallicity, which may affect discussions of the possible relationship between metallicity and exoplanets, as RV surveys are biased toward low LogR'_HK_ and possibly toward high-metallicity stars. We conclude that activity and metallicity strongly affect the small-scale convection levels in stars in the F7-K4 range, with a lower amplitude for the lower mass stars and a larger amplitude for low-metallicity stars.