Variability of HD 212044 during TESS sectors 16 and 17. (a) Normalized TESS SAP flux, with the orange line indicating the low-frequency trend. (b) Hα EW measurements (red points). The orange line represents the low-frequency trend line from panel (a), mirrored to match the EW variations. (c) Detrended flux, highlighting frequency beatings (see Sect. 4). (d) Wavelet analysis of the TESS signal, showing the frequency content over time. (e) Amplitude modulation corresponding to the beatings and intensity variations in the five frequencies with the highest amplitudes of the first (in green) and second (in blue) frequency groups. The red curve represents the vector sum combined effect of the two groups. Abscissas are in BTJD = BJD – 2457000 (details in Sect. 4).