Iron and nickel spectral opacity calculations in conditions relevant for pulsating stellar envelopes and experiments

D. Gilles (1), S. Turck-Chièze (1), M. Busquet (2), F. Thais (3), G. Loisel (4), L. Piau (1), J.E. Ducret (1), T. Blenski (3), C. Blancard (5), P. Cossé (5), G. Faussurier, F. Gilleron (5), J.C. Pain (5), Q. Porcherot (5), J.A. Guzik (6), D.P. Kilcrease (6), N.H. Magee (6), J. Harris (7), S. Bastiani-Ceccotti (8), F. Delahaye (9), C.J Zeippen (9).

(1) CEA/IRFU/Sap, F-91191 Gif-sur-Yvette, Cedex, France; (2) ARTEP Ellicott City, MD 21042, USA;  (3) CEA/IRAMIS/SPAM, F-91191 Gif-sur-Yvette, France; (4) Sandia National Laboratories, Albuquerque, NM 87185-1196, USA; (5) CEA/DIF, F-91297 Arpajon, France; (6) Theoretical Division, LANL, Los Alamos NM 87545, USA;  (7) AWE Readings Berkshire, RG7 4PR, UK; (8) LULI, Ecole Polytechnique, 91128 Palaiseau, France; (9) LERMA Observatoire de Paris-Meudon, France.

Seismology of stars is strongly developing. To address this question we have formed an international collaboration OPAC to perform specific experimental measurements, compare opacity calculations and improve the opacity calculations in the stellar codes [1]. We consider the following opacity codes: SCO, CASSANDRA, STA, OPAS, LEDCOP, OP, SCO-RCG. Their comparison has shown large differences for Fe and Ni in equivalent conditions of envelopes of type II supernova precursors, temperatures between 15 and 40 eV and densities of a few mg/cm3 [2, 3, 4]. LEDCOP, OPAS, SCO-RCG structure codes and STA give similar results and differ from OP ones for the lower temperatures and for spectral interval values [3]. In this work we discuss the role of Configuration Interaction (CI) and the influence of the number of used configurations. We present and include in the opacity code comparisons new HULLAC-v9 calculations [5, 6] that include full CI. To illustrate the importance of this effect we compare different CI approximations (modes) available in HULLAC-v9 [7]. These results are compared to previous predictions and to experimental data. Differences with OP results are discussed.

Complete preprint ==> http://arxiv.org/abs/1201.4692

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