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Session 72 - Open Clusters.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[72.11] The Iron Project: Atomic Data for the Iron Peak Elements

A. K. Pradhan, H. L. Zhang, S. N. Nahar, P. Romano, M. A. Bautista (Ohio State U.)

Almost all classes of astronomical objects exhibit spectral features of Fe ions and, in general, of ions of the iron-peak sequence. These are, therefore, of great diagnostic value across most wavelength ranges, from the hard X-ray and extreme UV up to the far IR. The IRON Project is an international collaboration devoted to the study of atomic process for all ions of the iron-group elements for applications in astrophysical and laboratory plasmas. For this purpose, the computer codes for atomic calculations using the R-matrix method in the close coupling approximation developed under the Opacity Project were extended to include relativistic Breit-Pauli effects. The codes were also adapted to run on a variety of computational platforms including massively parallel machine, e.g. Cray T3D and IBM SP2. Presently we report some recent results by the Ohio State group on collision strengths, radiative transition probabilities, photoionization cross section, and total electron-ion recombination rates for all carbon and nitrogen ions, Fe I-V, Fe XXII, Fe XXV, and Fe XXVI. An important feature of the present work is that accurate photoionization and recombination data are calculated for the first time in a self-consistent manner, as required in photoionization models. Carbon and nitrogen ionic fractions in coronal and photoionization equilibrium are presented and compared with previous works. The work is supported partially by the U.S. National Science Foundation (PHY-9421898), NASA LTSA program (NAGW-3315) and NASA ADP program (NAS5-32643

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