2019ApJ...878...28S

During the classical nova outburst, the radiation generated by the nuclear burning of hydrogen in the surface layer of a white dwarf (WD) is reprocessed by the outer material into different forms at softer energies, whose distribution in the spectrum depends on the nova age. Using the method of multiwavelength modeling the spectral energy distribution (SED), we determined physical parameters of the stellar, nebular, and dust component of radiation isolated from the spectrum of the classical nova V339 Del from day 35 to day 636 after its explosion. The transition from the iron-curtain phase to the supersoft source phase (days 35-72), when the optical brightness dropped by 3-4 mag, the absorbing column density fell by its circumstellar component from ∼1 x 10²³ to ∼1 x 10²¹ cm^–2, and the emission measure decreased from ∼2 x 10⁶² to ∼8.5 x 10⁶⁰ cm^–3, was caused by stopping down the mass loss from the WD. The day 35 model SED indicated an oblate shape of the WD pseudophotosphere and the presence of the dust located in a slow equatorially concentrated outflow. The dust emission peaked around day 59. Its coexistence with the strong supersoft X-ray source in the day 100 model SED constrained the presence of the disk-like outflow, where the dust can spend a long time. Both the SED models revealed a super-Eddington luminosity of the burning WD at a level of (1-2) x 10³⁹ (d/4.5 kpc)² erg s^–1, lasting from ∼day 2 to at least day 100.