The r-Process in Neutrino-driven Winds from Nascent, ``Compact'' Neutron Stars of Core-Collapse Supernovae
Abstract
We present calculations of r-process nucleosynthesis in neutrino-driven winds from the nascent neutron stars of core-collapse supernovae. A full dynamical reaction network for both the α-rich freezeout and the subsequent r-process is employed. The physical properties of the neutrino-heated ejecta are deduced from a general relativistic model in which spherical symmetry and steady flow are assumed. Our results suggest that proto-neutron stars with a large compaction ratio provide the most robust physical conditions for the r-process. The third peak of the r-process is well reproduced in the winds from these ``compact'' proto-neutron stars even for a moderate entropy, ~100NAk-200NAk, and a neutrino luminosity as high as ~1052 ergs s-1. This is due to the short dynamical timescale of material in the wind. As a result, the overproduction of nuclei with A<~120 is diminished (although some overproduction of nuclei with A~90 is still evident). The abundances of the r-process elements per event is significantly higher than in previous studies. The total integrated nucleosynthesis yields are in good agreement with the solar r-process abundance pattern. Our results have confirmed that the neutrino-driven wind scenario is still a promising site in which to form the solar r-process abundances. However, our best results seem to imply both a rather soft neutron-star equation of state and a massive proto-neutron star that is difficult to achieve with standard core-collapse models. We propose that the most favorable conditions perhaps require that a massive supernova progenitor forms a massive proto-neutron star by accretion after a failed initial neutrino burst.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2001
- DOI:
- 10.1086/321339
- arXiv:
- arXiv:astro-ph/0102261
- Bibcode:
- 2001ApJ...554..578W
- Keywords:
-
- Nuclear Reactions;
- Nucleosynthesis;
- Abundances;
- Stars: Abundances;
- Stars: Mass Loss;
- Stars: Neutron;
- Stars: Supernovae: General;
- Astrophysics
- E-Print:
- 12 pages, 6 figures, accepted for publication in the Astrophysical Journal