Theory of hydrogen shell flashes on accreting white dwarfs. I. Their progress and the expansion of the envelope

Journal Article · Tue Jun 15 00:00:00 EDT 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160029· OSTI ID:6705785

Fujimoto, M Y

By applying an analytical solution to the envelope, hydrogen shell flashes on accreting white dwarfs are computed semianlytically from their ignition to their final stage. When the mass of the white dwarf, M, and the mass of the hydrogen-rich envelope, ..delta..M/sub 1/, are specified, their progress is determined uniquely. Structural change and the resultant expansion of the envelope due to the shell flash depend mainly on the weight of overlying layer P(/sub 1/ or the product of the column mass above the burning shell and the surface gravity of the white dwarf. It is proved that this expansion is more rapid and greater for higher P(/sub 1/. When P(/sub 1/ is low (e.g.,< or approx. =4 x 10/sup 18/ dyn cm/sup -2/ for M = 1.0 M/sub sun/), the shell flash is weak, and the envelope settles in thermal equilibrium even before it expands to a solar radius. When P(/sub 1/ is high enough (10/sup 20/ dyn cm/sup -2/), on the other hand, the structural change is so violent that the expansion is accelerated beyond the escape velocity and leads directly to a nova explosion. Because of large P(/sub 1/, such a nova explosion requies a relatively large mass of the accreted envelope. The necessary mass of the envelope is as large as 10/sup -5/ M/sub sun/ even for white dwarfs close to the Chandrasekhar mass limit, and for less massive white dwarfs, it is still larger because of lower surface gravity. These results indicate that these nova explosions are phenomena which are related to surface gravity. These results indicate that these nova explosion are phenomena which are related to the slow accretion onto massive white dwarfs. Even for the optimal case of the most massive white dwarfs, the accretion rate should be lower than 10/sup -9/ M/sub sun/ yr/sup -1/.

• Research Organization: Department of Astronomy, University of Illinois
• OSTI ID: 6705785
• Journal Information: Astrophys. J.; (United States), Vol. 257:2
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
WHITE DWARF STARS
NUCLEOSYNTHESIS
STAR ACCRETION
STAR MODELS
STELLAR ATMOSPHERES
ANALYTICAL SOLUTION
EXPANSION
HYDROGEN BURNING
NOVAE
STAR EVOLUTION
ATMOSPHERES
DWARF STARS
ERUPTIVE VARIABLE STARS
MATHEMATICAL MODELS
STAR BURNING
STARS
VARIABLE STARS
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