Lomb-Scargle periodograms obtained from the variability of the double peak trough T (blue) and the Hα emission line centroid velocities (black). For comparison purposes, and due to the double-humped nature of the T modulation, we halved the frequencies corresponding to the periodogram associated with T. The horizontal black line shows the 99% white noise significance level. The pink and red vertical dashed lines mark the potential orbital periods found by Zurita et al. (2008) and Neustroev et al. (2014), respectively.