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The astrophysical r-process: A comparison of calculations following adiabatic expansion with classical calculations based on neutron densities and temperatures

Freiburghaus, C. and Rembges, J. F. and Rauscher, T. and Kolbe, E. and Thielemann, F. K. and Kratz, K. L. and Pfeiffer, B. and Cowan, J. J.. (1999) The astrophysical r-process: A comparison of calculations following adiabatic expansion with classical calculations based on neutron densities and temperatures. The astrophysical journal. Part 1, Vol. 516, H. 1. pp. 381-398.

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Official URL: http://edoc.unibas.ch/dok/A5839331

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Abstract

The rapid neutron-capture process (r-process) encounters unstable nuclei far from beta-stability. Therefore its observable features, like the abundances, witness (still uncertain) nuclear structure as well as the conditions in the appropriate astrophysical environment. With the remaining lack of a full understanding of its astrophysical origin, parameterized calculations are still needed. We consider two approaches: (1) the classical approach is based on (constant) neutron number densities n(n) and temperatures T over duration timescales tau; (2) recent investigations, motivated by the neutrino wind scenario from hot neutron stars after a supernova explosion, followed the expansion of matter with initial entropies S and electron fractions Y-e over expansion timescales tau. In the latter case the freezeout of reactions with declining temperatures and densities can be taken into account explicitly. We compare the similarities and differences between the two approaches with respect to resulting abundance features and their relation to solar r-process abundances, applying for the first time different nuclear mass models in entropy-based calculations. Special emphasis is given to the questions of (a) whether the same nuclear properties far from stability lead to similar abundance patterns and possible deficiencies in (1) and (2), and (b) whether some features can also provide clear constraints on the astrophysical conditions in terms of permitted entropies, Y-e values, and expansion timescales in (2). This relates mostly to the A > 110 mass range, where a fit to solar r-abundances in high-entropy supernova scenarios seems to be hard to attain. Possible low-entropy alternatives are presented.
Faculties and Departments:05 Faculty of Science > Departement Physik > Former Organization Units Physics > Theoretische Physik Astrophysik (Thielemann)
UniBasel Contributors:Rauscher, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:University of Chicago Press
ISSN:0004-637X
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:27 Mar 2014 13:12
Deposited On:14 Sep 2012 06:44

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