H α variability of the recurrent nova T Coronae Borealis ⋆

We analyze Hα observations of the recurrent nova T CrB obtained during the last decade. For the first time the Hα emission profile is analyzed after subtraction of the red giant contribution. Based on our new radial velocity measurements of the Hα emission line we estimate the component masses of T CrB. It is found that the hot component is most likely a massive white dwarf. We estimate the inclination and the component masses to be i ≃ 67 • , M WD ≃ 1.37 ± 0.13M ⊙ and M RG ≃ 1.12 ± 0.23M ⊙ , respectively. The radial velocity of the central dip in the Hα profile changes nearly in phase with that of the red giant's absorption lines. This suggests that the dip is most likely produced by absorption in the giant's wind. Our observations cover an interval when the Hα and the U-band flux vary by a factor of ∼ 6, while the variability in B and V is much smaller. Based on our observations, and archival ultraviolet and optical data we show that the optical, ultraviolet and Hα fluxes strongly correlate. We argue that the presence of an accretion disc can account for most of the observed properties of T CrB.