Upper left: scargle periodogram of  ⟨ v ⟩  of the He i line at 6678 Å  with the highest peak at  ~2.23   d^-1. Upper right: phase-plot of  ⟨ v ⟩  according to the frequency f_m = 2.228748   d^-1. The small symbols are observations, while the larger red circles are phase-binned averages. Lower left: Θ_PDM-statistics of  ⟨ v ⟩ , showing the deepest minimum at f_m/2. Lower right: phase-plot of  ⟨ v ⟩  according to the frequency f_m/2.