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We present the results of simultaneous spectroscopic and photometricobservations of the cataclysmic variable star (hereafter CVs) V455 Andromedae,belonging to the WZ Sge sub-class, in quiescence. Using the spectroscopic datawe computed time-resolved Doppler tomograms of the system demonstrating itsbehavior at different orbital phases. In the tomograms one can see the periodicbrightening of different regions within one orbital cycle. We interpret thisbrightening as being due to the interaction of four phase-locked shock waves inthe disk with a specific internal precessing density wave that develops insidethe disk, because of the tidal influence of the secondary star, and thisdensity wave propagates up to the disk's outer regions. When the outer part ofthe density wave in its precessional motion reaches a shock wave the localdensity grows, which amplifies the shock (by increasing $\rho V^{2}/2$). Thisresults in an additional energy release in the shock and can be observed as abrightening. Analysis of the tomographic results and the photometric data showsthat two main sources contribute to the light curves of the system: theradiation of the "hot line" and the bow-shock gives us two major orbital humps,located approximately at the orbital phases $\phi=0.25$ and $\phi=0.75$; theamplification of the four shock waves may give us up to four "superhumps"shifting over the light curve with the precessional period. These two effects,when overlapping, change the shape of the light curves, shift the hump maxima,and they sometimes produce more than two humps in the light curve. We shouldemphasize that when saying "superhumps" we imply an effect that is observed inquiescent light curves of WZ Sge stars, as opposed to "classical" superhumpsusually observed in outbursts.

On the nature of quiescent light curves demonstrated by WZ Sge stars