Low-temperature photonuclear nucleosynthesis of the bypassed (p-) nuclei in degenerate hydrogen burning zones and its relationship to nova outbursts
We have investigated the likelihood that the canonical p-nuclei (bypassed nuclei) may have been synthesized, at least in part, within degenerate hydrogen burning zones via low temperature photonuclear reactions triggered by photons released through proton capture by triply heavy hydrogen (/sup 3/T). For combinations of temperatures generally less than T/sub 6/=15, and densities greater than 10,000 g cm/sup -3/, the hydrogen burning cycle closes via the /sup 3/He(e/sup -/)/sup 3/T(p,..gamma..)/sup 4/Hebranch. The /sup 3/T(p,..gamma..)/sup 4/He photon is the most energetic (approx.20 MeV) known to be due to proton capture inside stars. This allows for the (..gamma..,n) and (..gamma..,2n) synthesis and destruction of the p-nuclei.We show that a likely astrophysical site for the photonuclear synthesis of the nuclei exists in white dwarfs accreting surface layers of hydrogen-rich material, eventually leading to nova outbursts as shown by Starrfield, Truran, and Sparks. In order to produce a nova outburst the accreting object must initially be of low luminosity, and this initial condition is sufficient for the ejection of processed matter into the interstellar medium. To determine the physical conditions within the degenerate hydrogen burning shell, we make use of the recent models by Sienkowicz which suggest, but do not conclusively demonstrate, that for the stationary shell approximation, the bypassed nuclei can be synthesized and the initial conditions established for the subsequent nova outburst.Under the conditions of degenerate hydrogen burning, we compute the abundances for several exposure periods, and find reasonable agreement with that for observed solar system p-nuclei, providing the solar s-nuclei distribution characterizes that for the seed nuclei. The strongest feature of the model is its ability to reproduce the isotopic abundance ratios of the double p-nuclei such as those for tin, xenon, barium, etc., and overabundances of heavy nuclei in the mass range 120< or =A< or =196.
- Research Organization:
- Department of Physics, North Texas State University, Denton
- OSTI ID:
- 5041534
- Journal Information:
- Astrophys. J., Suppl. Ser.; (United States), Vol. 36:1
- Country of Publication:
- United States
- Language:
- English
Similar Records
UNSTABLE HELIUM SHELL BURNING ON ACCRETING WHITE DWARFS
Development of a Monte Carlo code for the data analysis of the {sup 18}F(p,α){sup 15}O reaction at astrophysical energies
Related Subjects
GENERAL PHYSICS
NOVAE
PHOTONUCLEAR REACTIONS
NUCLEOSYNTHESIS
ABUNDANCE
CAPTURE
COMPTON EFFECT
ISOTOPE RATIO
NUCLEI
PHOTONS
PROTON REACTIONS
STAR ACCRETION
STAR MODELS
TRITIUM
BARYON REACTIONS
BASIC INTERACTIONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
HADRON REACTIONS
HYDROGEN ISOTOPES
INTERACTIONS
ISOTOPES
LIGHT NUCLEI
MASSLESS PARTICLES
MATHEMATICAL MODELS
NUCLEAR REACTIONS
NUCLEON REACTIONS
ODD-EVEN NUCLEI
RADIOISOTOPES
SCATTERING
STAR EVOLUTION
STARS
YEARS LIVING RADIOISOTOPES
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources