Multiplicity of Nova Envelope Solutions and Occurrence of Optically Thick Winds

We revisit the occurrence condition of optically thick winds reported by Kato (1985) and Kato & 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 M⊙. With the OPAL opacity we find that the optically thick wind occurs for & 0.6 M⊙ 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 M⊙. 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. Subject headings: binaries: symbiotic — novae, cataclysmic variables — stars: individual (PU Vul) — stars: interiors — stars: mass loss