Top panel: periodogram of the simulated radial velocity time series of a Sun-like star showing sectoral r modes with m = 2 and 3 as seen with an inclination i = 60°. The RV amplitudes and the periods of the modes are given in Table 1; they correspond to a maximum horizontal velocity of the modes of 2 m s⁻¹ at the stellar surface. The periodogram is normalized according to the definition of the GLS given by Zechmeister & Kürster (2009). A normally distributed random noise with a standard deviation σ_n of 10 cm s⁻¹ was added. The vertical dashed line indicates the period of the m = 2 mode and the dotted line that of the m = 3 mode. The red horizontal line gives the level of 1% FAP as determined by analyzing 10 000 random shufflings of the original time series. Bottom panel: same as the top panel, but for a standard deviation of the noise σ_n of 50 cm s⁻¹. Here the red horizontal line indicates the level corresponding to a FAP of 2%.