New binary parameters for the symbiotic recurrent nova T Coronae Borealis

The amplitude of the ellipsoidal variability, the mass function, and the evolutionary limits on the component masses have been used to constrain the binary system parameters. Contrary to all previous studies, our analysis shows that the mass ratio of T CrB q(M_giant/M_hot)=0.6, which implies a low mass binary system, with the stellar masses M_giant=0.7 solar mass, and M_hot=1.2 solar mass. This result strongly supports the thermonuclear runaway model for this recurrent nova, and solves all controversies about the nature of the hot component and the physical causes of its eruptions.