AM CVn -- System Parameters and Gravitational Waves

Abstract

System parameters are re-determined: $M_1=0.86\pm 0.18M\odot$, $M_2=0.103\pm 0.022M\odot$, $A=1.508\pm 0.100\times 10^{10}$cm, and $i=69\pm 3^{\circ }$. The secondary component is a semi-degenerate helium star loosing mass at a rate $\dot{M}=4.93\pm 1.65\times 10^{-9}M\odot /yr$. 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 $\varphi =0.50$, corresponding to $O-C=0.0060$d. Together with mimima observed in 1992-99 this implies that the orbital period is increasing at a rate $dP/dt\approx 8.5\times 10^{-13}$ consistent with predictions involving the emission of gravitational waves.

Submitted to "Acta Astronomica"