2001ApJ...562..887T -
Astrophys. J., 562, 887-908 (2001/December-1)
The physics of proto-neutron star winds: implications for r-process nucleosynthesis.
THOMPSON T.A., BURROWS A. and MEYER B.S.
Abstract (from CDS):
We solve the general-relativistic steady-state eigenvalue problem of neutrino-driven proto-neutron star winds, which immediately follow core-collapse supernova explosions. We provide velocity, density, temperature, and composition profiles and explore the systematics and structures generic to such a wind for a variety of proto-neutron star characteristics. Furthermore, we derive the entropy, dynamical timescale, and neutron-to-seed ratio in the general relativistic framework essential in assessing this site as a candidate for r-process nucleosynthesis. Generally, we find that for a given mass outflow rate (M{dot}), the dynamical timescale of the wind is significantly shorter than previously thought. We argue against the existence or viability of a high entropy (≳300 per kB per baryon), long dynamical timescale r-process epoch. In support of this conclusion, we model the proto-neutron star cooling phase, calculate nucleosynthetic yields in our steady-state profiles, and estimate the integrated mass loss. We find that transonic winds enter a high-entropy phase only with very low M{dot} (≲1x10–9 M☉ s–1) and extremely long dynamical timescale (τρ≳0.5 s). Our results support the possible existence of an early r-process epoch at modest entropy (∼150) and very short dynamical timescale, consistent in our calculations with a very massive or very compact proto-neutron star that contracts rapidly after the preceding supernova. We explore possible modifications to our models, which might yield significant r-process nucleosynthesis generically. Finally, we speculate on the effect of fallback and shocks on both the wind physics and nucleosynthesis. We find that a termination or reverse shock in the wind, but exterior to the wind sonic point, may have important nucleosynthetic consequences. The potential for the r-process in proto-neutron star winds remains an open question.
Abstract Copyright:
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Journal keyword(s):
Nuclear Reactions, Nucleosynthesis, Abundances - Stars: Mass Loss - Stars: Neutron - Stars: Supernovae: General
Simbad objects:
3
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