Distribution of measured characteristic frequencies, ν_char, as a function of stellar parameters given in solar units. The grey line represents the granulation frequency scaled using Eq. (3) with the Sun’s location indicated by the ⊙ symbol. The circles have been colour-coded by a star’s spectroscopic luminosity and the size of the symbol is proportional to the fitting parameter, α₀. White triangles represent stars which may have insufficient CoRoT data for an accurate determination for the fitting parameter γ (cf. Eq. (3)).