2025ApJ...984..136H

The classical nova V392 Per 2018 is characterized by a very fast optical decline, a long binary orbital period of 3.23 days, detection of GeV gamma rays, and almost identical decay trends of the B, V, and I_C light curves. The last feature is unique because most novae develop strong emission lines in the nebular phase and these lines contribute especially to the B and V bands and cause large differences between the BV and I_C light curves. This unique feature can be understood if the optical flux is dominated by continuum until the late phase of the nova outburst. Such continuum radiation is emitted by a bright accretion disk irradiated by a hydrogen-burning white dwarf (WD) and a viscous heating disk with a high mass accretion rate after the hydrogen burning ends. We present a comprehensive nova outburst model that reproduces all of these light curves. We determine the WD mass to be M_WD = 1.35-1.37 M_⊙ and the distance modulus in the V band to be (m - M)_V = 14.6 ± 0.2; the distance is d = 3.45 ± 0.5 kpc for the reddening of E(B - V) = 0.62.