Multiplicity of Nova Envelope Solutions and Occurrence of Optically Thick Winds

TL;DR

This paper revisits conditions for optically thick winds in nova envelopes, revealing that wind occurrence depends on white dwarf mass and ignition mass, with static solutions explaining slow nova evolutions like PU Vul.

Contribution

It demonstrates that with updated OPAL opacity, optically thick winds can occur in lower mass WDs and introduces the role of ignition mass and static solutions in nova evolution.

Findings

Optically thick winds occur in WDs >~ 0.6 Mo with OPAL opacity.

Winds are suppressed by density-inversion layers at high ignition masses.

Static solutions explain slow nova evolutions like PU Vul.

Abstract

We revisit the occurrence condition of optically thick winds reported by Kato (1985) and Kato and Hachisu (1989) who examined mathematically nova envelope solutions with an old opacity and found that optically thick winds are accelerated only in massive white dwarfs (WDs) of >~ 0.9 Mo. With the OPAL opacity we find that the optically thick wind occurs for >~ 0.6 Mo WDs and that the occurrence of winds depends not only on the WD mass but also on the ignition mass. When the ignition mass is larger than a critical value, winds are suppressed by a density-inversion layer. Such a static solution can be realized in WDs of mass ~0.6-0.7 Mo. We propose that sequences consisting only of static solutions correspond to slow evolutions in symbiotic novae like PU Vul because PU Vul shows no indication of strong winds in a long-lasted flat peak followed by a very slow decline in its light curve.