Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

Farouqi, K. and Kratz, K. -L. and Pfeiffer, B. and Rauscher, T. and Thielemann, F. -K. and Truran, J. W.. (2010) Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae. The astrophysical journal. Part 1, Vol. 712, H. 2. pp. 1359-1377.

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Official URL: http://edoc.unibas.ch/dok/A5840158

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The astrophysical site of the r-process is still uncertain, and a full exploration of the systematics of this process in terms of its dependence on nuclear properties from stability to the neutron drip-line within realistic stellar environments has still to be undertaken. Sufficiently high neutron-to-seed ratios can only be obtained either in very neutron-rich low-entropy environments or moderately neutron-rich high-entropy environments, related to neutron star mergers (or jets of neutron star matter) and the high-entropy wind of core-collapse supernova explosions. As chemical evolution models seem to disfavor neutron star mergers, we focus here on high-entropy environments characterized by entropy S, electron abundance Y-e, and expansion velocity V-exp. We investigate the termination point of charged-particle reactions, and we define a maximum entropy S-final for a given V-exp and Y-e, beyond which the seed production of heavy elements fails due to the very small matter density. We then investigate whether an r-process subsequent to the charged-particle freeze-out can in principle be understood on the basis of the classical approach, which assumes a chemical equilibrium between neutron captures and photodisintegrations, possibly followed by a beta-flow equilibrium. In particular, we illustrate how long such a chemical equilibrium approximation holds, how the freeze-out from such conditions affects the abundance pattern, and which role the late capture of neutrons originating from beta-delayed neutron emission can play. Furthermore, we analyze the impact of nuclear properties from different theoretical mass models on the final abundances after these late freeze-out phases and beta-decays back to stability. As only a superposition of astrophysical conditions can provide a good fit to the solar r-abundances, the question remains how such superpositions are attained, resulting in the apparently robust r-process pattern observed in low metallicity stars.
Faculties and Departments:05 Faculty of Science > Departement Physik > Former Organization Units Physics > Theoretische Physik Astrophysik (Thielemann)
UniBasel Contributors:Rauscher, Thomas and Thielemann, Friedrich-Karl
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:University of Chicago Press
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:27 Mar 2014 13:12
Deposited On:14 Sep 2012 06:47

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