Physics of nova outbursts: A theoretical model of classical nova outbursts with self-consistent wind mass loss

Abstract

We present a model for one cycle of a classical nova outburst based on a self-consistent wind mass loss accelerated by the gradient of radiation pressure, i.e., the so-called optically thick winds. Evolution models are calculated by a Henyey code for a 1.0 $M_\odot$ white dwarf (WD) with a mass accretion rate of $5 \times 10^{-9}~M_\odot$ yr$^{-1}$. The outermost part of hydrogen-rich envelope is connected to a steadily moving envelope when optically thick winds occur. We confirm that no internal shock waves occur at the thermonuclear runaway. The wind mass loss rate reaches a peak of $1.4 \times 10^{-4}~M_\odot$ yr$^{-1}$ at the epoch of the maximum photospheric expansion, where the photospheric temperature decreases to $\log T_{\rm ph}$ (K)=3.90. Almost all of the accreted mass is lost in the wind. The nuclear energy generated in hydrogen burning is lost in a form of photon emission (64 %), gravitational energy (lifting-up the wind matter against the gravity, 35 %), and kinetic energy of the wind (0.23 %). A classical nova should be very bright in a far-UV (100 - 300 \AA) band, during a day just after the onset of thermonuclear runaway ($\sim$25 d before the optical maximum). In the decay phase of the nova outburst, the envelope structure is very close to that of a steady state solution.