2024PASJ...76..666K

We present time-dependent nova outburst models with optically thick winds for 1.2 and 1.35$\, M_{\odot }$ white dwarfs (WDs) with a mass-accretion rate of $5 \times 10^{-9}\, M_{\odot }$ yr^–1 and for a 1.3$\, M_{\odot }$ WD with $2 \times 10^{-9}\, M_{\odot }$ yr^–1. The X-ray flash occurs 11 d before the optical peak of the 1.2$\, M_{\odot }$ WD and 2.5 d before the peak of the 1.3$\, M_{\odot }$ WD. The wind mass-loss rate of the 1.2$\, M_{\odot }$ WD (1.3$\, M_{\odot }$ WD) reaches a peak of $6.4 \times 10^{-5}\, M_{\odot }$ yr^–1 ($7.4 \times 10^{-5}\, M_{\odot }$ yr^–1) at the epoch of the maximum photospheric expansion with the lowest photospheric temperature of log T_ph (K) = 4.33 (4.35). The nuclear energy generated during the outburst is lost in the form of radiation (61% for the 1.2$\, M_{\odot }$ WD; 47% for the 1.3$\, M_{\odot }$ WD), gravitational energy of ejecta (39%; 52%), and kinetic energy of the wind (0.28%; 0.29%). We found an empirical relation for fast novae between the time to optical maximum from the outburst t_peak and the expansion timescale τ_exp. With this relation, we are able to predict the time to optical maximum t_peak from the ignition model (at t = 0) without following a time-consuming nova wind evolution.