Histograms of the the gradient-like function β₁₂ for 637 stars with 16 < P < 30 days obtained with bin widths 0.468 and 0.090 in (panel a) and (panel b), respectively. Panel c: shows the histogram features at the distribution maxima in (panel b) with the labeled probability of exceeding the specified levels (pointed lines), according to the binomial distribution (Eq. (2)). The vertical dashed line indicates the prediction of Kolmogorov’s theory of turbulence β₁₂ = −2∕3. The value n is the number of β₁₂ estimates in one bin of the histogram.