SIMBAD references

For all the AM CVn objects we observe harmonic structure in the FT of their light curves. From recent advances in the theory of accretion discs we now can relate the harmonic structures to physical structures in the discs. Numerical simulations provide us with tools to interpret the pattern resulting from the tidal disc responses and non-linear coupling between response modes. From WET photometry it may be possible to observe the evolution of modes when objects go from low state to high state. This may help us to understand the physics of accretion discs and to test disc theories.