AM CVn - System Parameters and Gravitational Waves

System parameters of AM CVn are re-determined: M1=0.86±0.18 M☉, M2=0.103±0.0022 M☉, A=1.508±0.100×1010 cm, and i=69±3°. The secondary component of the system is a semi-degenerate helium star loosing mass at a rate M=4.93±1.65×10-9 M☉/yr. The accretion disk is sufficiently hot to avoid thermal instability. The orbital light curve recovered from observations made in 1962 shows minimum shifted to phase φ=0.50, corresponding to O-C=0.0060 d. Together with mimima observed in the years 1992-1999 this implies that the orbital period is increasing at a rate of dP/dt≈8.5×10-13 - consistent with predictions involving the emission of gravitational waves.