Variability and activity indicators as a function of stellar mass. Top panel: Distribution of ΔEW = max(EW) – min(EW) for Hα emission. The dashed black line shows a linear fit, ΔEW_Hα = a(M_*) + b, with a = 7.71 ± 1.55, b = −7.38 ± 0.64. Bottom panel: Median values of log₁₀(L_Hα/L_bol) for Hα emission as a function of stellar mass. The black squares mark the medians in seven equally spaced bins with scatter quantified using the median absolute deviation. The blue circles are scaled by P_rot, and larger circles correspond to longer P_rot. The filled red circles indicate stars without a measured rotation period. The vertical gray lines show the bin sizes.