Envelope models for the supersoft X-ray emission of V1974 Cyg

The evolution of the soft X-ray emission of V1974 Cyg has been simulated by a white dwarf envelope model with steady hydrogen burning. The comparison of the results obtained from ROSAT observations with the results of our envelope models indicates that the post-outburst evolution of the nova can be explained by steady H-burning on either a 0.9 $M_{\odot }$ white dwarf with 50% degree of mixing between solar-like accreted material and the ONe degenerate core, or on a 1.0 $M_{\odot}$ ONe white dwarf with 25% mixing.