Evolutionary tracks in the log g versus log T_eff plane for the various sets of metallicities and helium abundance, for α = 1.8 (see text for details). The symbols indicate the error boxes of Gonzalez et al. (2001) (asterisks), Santos et al. (2004) (diamonds), Gillon & Magain (2006) (squares), Fisher & Valenti (2005) (triangles), and Ballot et al. (2011) (crosses). The straight thick line represents the iso-⟨Δν⟩ line, with ⟨Δν⟩ = 98.4 μHz.