Top panel: Rotation periods as a function of effective temperature for the sample of 243 1 M_⊙ stars described in Section 2. Data points are color-coded by the values of the convective plasma parameter, and the gray bars indicate the observational uncertainties in the rotation periods. A linear regression fit to the data yields a Spearman correlation coefficient of ρ = −0.21 with a p-value of 1.4 × 10⁻⁵. Bottom panel: Convective plasma parameter (Eq. 4) as a function of effective temperature for the same set of stars. Data points are color-coded by the measured rotation periods. A linear regression fit yields a Spearman correlation coefficient of ρ = −0.27 with a p-value of 1.2 × 10⁻³. For reference, the solar values are indicated by the symbol ⊙. The theoretical solar model is computed using the GS98 metallicity.