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Advances in atomic data for neutron-capture elements

Published online by Cambridge University Press:  30 August 2012

Nicholas C. Sterling
Affiliation:
Department of Physics and Astronomy, Michigan State University, 3248 Biomedical Physical Sciences, East Lansing, MI 38824-2320, USA, email: sterling@pa.msu.edu
Michael C. Witthoeft
Affiliation:
NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA Department of Astronomy, University of Maryland, College Park, MD 20742, USA
David A. Esteves
Affiliation:
JILA, University of Colorado, Boulder, CO 80309-0440, USA
Phillip C. Stancil
Affiliation:
Department of Physics and Astronomy and the Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451, USA
A. L. David Kilcoyne
Affiliation:
The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Rene C. Bilodeau
Affiliation:
The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Western Michigan University, MS 5252, 1903 W., Michigan Ave., Kalamazoo, MI 49008, USA
Alejandro Aguilar
Affiliation:
The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Abstract

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Neutron(n)-capture elements (atomic number Z > 30), which can be produced in planetary nebula (PN) progenitor stars via s-process nucleosynthesis, have been detected in nearly 100 PNe. This demonstrates that nebular spectroscopy is a potentially powerful tool for studying the production and chemical evolution of trans-iron elements. However, significant challenges must be addressed before this goal can be achieved. One of the most substantial hurdles is the lack of atomic data for n-capture elements, particularly that needed to solve for their ionization equilibrium (and hence to convert ionic abundances to elemental abundances). To address this need, we have computed photoionization cross sections and radiative and dielectronic recombination rate coefficients for the first six ions of Se and Kr. The calculations were benchmarked against experimental photoionization cross section measurements. In addition, we computed charge transfer (CT) rate coefficients for ions of six n-capture elements. These efforts will enable the accurate determination of nebular Se and Kr abundances, allowing robust investigations of s-process enrichments in PNe.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

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