Top: dynamical spectra of the Hα (left) and He Iλ6678 (right) lines in Doppler space phased using the ephemeris given in Table 1, compared to the derived orbit (red line). The Hα line is mean-subtracted to enhance the contrast. Bottom: two HERMES spectra taken close to quadrature (see legend) of the Hα and He Iλ6678 lines, as in the top panel. The Hα line exhibits a narrow emission peak on top that traces the orbit of the primary star.