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

TL;DR

This paper develops a self-consistent theoretical model of classical nova outbursts, emphasizing wind mass loss driven by radiation pressure, and provides detailed insights into the energy distribution and observational signatures of the outburst.

Contribution

It introduces a comprehensive model of nova outbursts with self-consistent wind mass loss, connecting envelope structure to observable phenomena and energy budget.

Findings

Wind mass loss peaks at 1.4 x 10^-4 M_sun/yr during maximum expansion.

Most accreted mass is lost via wind, with 64% of nuclear energy emitted as photons.

Novae are predicted to be very bright in far-UV shortly after thermonuclear runaway.

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.