Pearson correlation, ℛ, between the temperature-binned RVs and the S index. The stars are ordered by effective temperature. The marker size indicates the median S/N of the studied spectra of each star, and the marker color indicates the power, P, of the largest periodogram peak of the S index relative to its 0.01% FAP level. The color map inverts at 1, such that green points represent periodograms peaks above the 0.01% FAP, and red points represent peaks below it.