Abstract

The online atomic database of NORAD-Atomic-Data, where NORAD stands for Nahar OSU Radiative, is part of the data sources of the two international collaborations of the Opacity Project (OP) and the Iron Project (IP). It contains large sets of parameters for the dominant atomic processes in astrophysical plasmas, such as, (i) photo-excitation, (ii) photoionization, (iii) electron–ion recombination, (iv) electron–impact excitations. The atomic parameters correspond to tables of energy levels, level-specific total photoionization cross-sections, partial photoionization cross-sections of all bound states for leaving the residual ion in the ground state, partial cross-sections of the ground state for leaving the ion in various excited states, total level-specific electron–ion recombination rate coefficients that include both the radiative and dielectronic recombination, total recombination rate coefficients summed from contributions of an infinite number of recombined states, total photo-recombination cross-sections and rates with respect to photoelectron energy, transition probabilities, lifetimes, collision strengths. The database was created after the first two atomic databases, TOPbase under the OP and TIPbase under the IP. Hence the contents of NORAD-Atomic-Data are either new or from repeated calculations using a much larger wave function expansion making the data more complete. The results have been obtained from the R-matrix method using the close-coupling approximation developed under the OP and IP, and from atomic structure calculations using the program SUPERSTRUCTURE. They have been compared with available published results which have been obtained theoretically and experimentally, and are expected to be of high accuracy in general. All computations were carried out using the computational facilities at the Ohio Supercomputer Center (OSC) starting in 1990. At present it contains atomic data for 154 atomic species, 98 of which are lighter atomic species with nuclear charge Z ≤ 28 and 56 are heavier ones with Z > 28. New data are added with publications.

Highlights

  • NORAD-ATOMIC-DATAThe online atomic database NORAD-Atomic-Data [1] was established at the Ohio State University in 2007 at the suggestion of astronomers and initiative of Dr C

  • These parameters have been obtained mainly from the R-matrix method using R-matrix package of codes developed under the Opacity Project (OP) and Iron Project (IP) [9,10,11] and their extensions for theoretical spectroscopy in LS coupling (e.g., [12]), for fine structure splitting of transitions (e.g., [13]), for fine structure spectroscopy (e.g., [14,15]), from the unified method for electron–ion recombination calculations (e.g., [16,17,18]), and from atomic structure calculations using the code SUPERSTRUCTURE (SS) [19,20]

  • Systematic studies‘ of radiative processes of photoexcitations and photoionization with resonances were carried out for all astrophysically abundant atoms and ions from hydrogen to iron for the first time by a team of 25 investigators in Europe, US, and South America

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Summary

Introduction

The online atomic database NORAD-Atomic-Data [1] was established at the Ohio State University in 2007 at the suggestion of astronomers and initiative of Dr C. NORAD contains a vast number of parameters for the four dominant atomic processes, which are described below, involving the interaction of a photon or electron and an ion that contribute the most to the spectra of astrophysical and laboratory plasmas These parameters have been obtained mainly from the R-matrix method using R-matrix package of codes developed under the OP and IP [9,10,11] and their extensions for theoretical spectroscopy in LS coupling (e.g., [12]), for fine structure splitting of transitions (e.g., [13]), for fine structure spectroscopy (e.g., [14,15]), from the unified method for electron–ion recombination calculations (e.g., [16,17,18]), and from atomic structure calculations using the code SUPERSTRUCTURE (SS) [19,20]. Individual transitions form spectral lines, data for a large number of transitions are needed to determine the opacity in plasmas, modeling synthetic spectra

Photoionization
Electron–Ion Recombination
The Opacity Project and atomic database TOPbase
The Iron Project and atomic database TIPbase
NORAD-ATOMIC-DATA and Atomic Astrophysics and Spectroscopy
Theoretical Approximations
Data Description of NORAD-Atomic-Data
Accuracy of Data and Benchmarking
Findings
Conclusions
Full Text
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