GLS periodograms for GJ 3779 CARMENES RVs (panel a) and its residuals (panel b) after removing the prominent peak at f = 0.3307 d^-1 (P = 3.023 d), marked in red. Panel c: periodogram of a photometric campaign of MEarth data from 2010. The highest peak at f_rot = 0.0105 d^-1 (P = 95.2 d) associatedwith the star’s rotation is marked with a solid blue line and its first harmonic (2f_rot) with a dashed blue line. Panels d–f: periodograms of the chromatic index, differential line width, and Hα index, while panels g–i show periodograms for the cross-correlation function FWHM, contrast, and bisector velocity span. Horizontal lines show the theoretical FAP levels of 10%(short-dashed line), 1% (long-dashed line), and 0.1% (dot-dashed line) for each panel.