CD diagram showing asteroseismic measurements – the small frequency separation δν and the large frequency separation Δν – for the sample of 97 solar-like stars studied here. The panels are arranged by metallicity. The points are colored by spectral type: F (blue, T_eff >  6000 K), G (orange, 6000 ≥ T_eff >  5200 K), K (red, T_eff ≤ 5200 K). The cross in the bottom right corner of each panel shows typical uncertainties (see also Fig. 5). The dotted light gray line indicates where δν = 0. The solid lines trace theoretical tracks of stellar evolution, with each track labeled along the top by its mass (in solar units) and connected by the dashed lines that are spaced in core-hydrogen abundance (X_c).