A new interpretation for the second peak of T Coronae Borealis outbursts: A tilting disk around a very massive white dwarf

A new interpretation for the second peak of T Coronae Borealis outbursts is proposed based on a thermonuclear runaway (TNR) model. The system consists of a very massive white dwarf (WD) with a tilting accretion disk and a lobe-filling red giant. The first peak of the visual light curve of T CrB outbursts is well reproduced by the TNR model on a WD close to the Chandrasekhar mass (M_WD ≳ 1-35 M_⊙), while the second peak is reproduced by the combination of the irradiated M giant and the irradiated tilting disk. The derived fitting parameters are the WD mass M_WD ∼ 1.35 M_⊙, the M giant companion mass M_RG ∼ 0.7 M_⊙ (0.6-1.0 M_⊙ is acceptable), the inclination angle of the orbit i ∼ 70°, and the tilting angle of the disk i_prec ∼ 35°. These parameters are consistent with the recently derived binary parameters of T CrB.