The χ² landscapes (“periodograms”), which result from fitting the Tycho and Hipparcos epoch photometry data (top) and the ASAS light-curve (bottom) with the model given in Eq. (C.1), as a function of the oscillation period: the differences Δχ² are with regard to the respective best fit given in Table C.1. A step size of 10 s is used to sample the oscillation period. The red line is the 4% false-alarm probability threshold deduced from Monte Carlo simulations (see Appendix C for details).