Spectroscopic orbits for symbiotic stars. I. The recurrent nova T Coronae Borealis.

The authors report new radial-velocity measurements of the giant component in the recurrent nova T Coronae Borealis. These data have been combined with existing observations to derive a new orbital solution and confirm previous estimates for the component masses. The orbital data and recent optical and ultraviolet spectra provide new support for a model in which a lobe-filling gM3 star loses material to a main-sequence companion star at a rate of ≡10^-6M_sun;yr^-1. T CrB appears to be at the onset of runaway case C mass exchange, and the authors expect an increase in the luminosity of the hot object over the next few decades.