CLOUDY is a large‐scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. Here we describe version 90 (C90) of the code, paying particular attention to changes in the atomic database and numerical methods that have affected predictions since the last publicly available version, C84. The computational methods and uncertainties are outlined together with the direction future development will take. The code is freely available and is widely used in the analysis and interpretation of emission‐line spectra. Web access to the Fortran source for CLOUDY, its documentation Hazy, and an independent electronic form of the atomic database is also described.

https://iopscience.iop.org/article/10.1086/316190/pdf

CLOUDY 90: Numerical Simulation of Plasmas and Their Spectra

This compilation revises the 1991 listing of atomic data for the lighter elements from hydrogen to gallium. The tabulation emphasizes resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 911.753 ?. All but the very weakest known and predicted electric-dipole transitions are included, but no forbidden lines. This paper has attempted to review all data published by the end of 2002.?????The tables contain the best data available to the author on ionization potentials, level designations, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often used combinations of log gf and log ?f. All ion stages with relevant classified lines are included. Individual components resulting from isotope shift and hyperfine structure are listed explicitly for certain species. The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed.?????This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels. The data also are relevant to the study of stellar atmospheres, and gaseous nebulae.?????An Appendix summarizes new data relevant to the similar compilation in Paper II for the elements germanium to uranium.

https://iopscience.iop.org/article/10.1086/377639/pdf

Atomic Data for Resonance Absorption Lines. III. Wavelengths Longward of the Lyman Limit for the Elements Hydrogen to Gallium

We report the creation of thermal, Fock, coherent, and squeezed states of motion of a harmonically bound {sup 9}Be{sup +} ion. The last three states are coherently prepared from an ion which has been initially laser cooled to the zero point of motion. The ion is trapped in the regime where the coupling between its motional and internal states, due to applied (classical) radiation, can be described by a Jaynes-Cummings-type interaction. With this coupling, the evolution of the internal atomic state provides a signature of the number state distribution of the motion. {copyright} {ital 1996 The American Physical Society.}

Generation of Non-classical Motional States of a Trapped Atom

A Calculation of Atomic Structures. By D. R. Hartree Pp. xiii, 181. 40s. 1957. (Wiley, New York)

We present the fifth release of the UMIST Database for Astrochemistry (UDfA). The new reaction network contains 6173 gas-phase reactions, involving 467 species, 47 of which are new to this release. We have updated rate coefficients across all reaction types. We have included 1171 new anion reactions and updated and reviewed all photorates. In addition to the usual reaction network, we also now include, for download, state-specific deuterated rate coefficients, deuterium exchange reactions and a list of surface binding energies for many neutral species. Where possible, we have referenced the original source of all new and existing data. We have tested the main reaction network using a dark cloud model and a carbon-rich circumstellar envelope model. We present and briefly discuss the results of these models.

The UMIST database for astrochemistry 2012

Atomic transition rates and f values have been calculated in the triplet and quintet systems and for some intercombination lines of neutral oxygen. Configuration interaction was included in the calculations performed with the CIV3 code of Hibbert (1975) for all the transitions connecting the n=3 and n=4 energy levels. In order to reproduce the observed energy splittings between the energy states, small empirical adjustments were introduced to the diagonal matrix elements. Comparisons with previously published f values and radiative lifetimes are discussed and the subsequent astrophysical applications of the results are briefly mentioned.

E1 transitions of astrophysical interest in neutral oxygen

Elaborate multiconfiguration Hartree-Fock wave functions have been obtained for the 4s $^{2}$S, 3d $^{2}$D, and 4p $^{2}$P\ifmmode^\circ\else\textdegree\fi{} states in ${\mathrm{Ca}}^{+}$ in order to investigate the core-valence correlation effects on the transition probabilities of the electric dipole (E1) and quadrupole (E2) processes involving these levels. In parallel, model-potential calculations using a core-polarization potential have been performed. They support the large reduction of the oscillator strengths found in the ab initio approach for both the E1 and E2 processes. The agreement between the two sets of results is satisfactory only if the polarization term is included in the Hartree-Fock variational procedure. The present theoretical $^{2}$P${\mathrm{\ifmmode^\circ\else\textdegree\fi{}}}_{1/2,3/2}$ lifetime values differ by 3.5% from the most recent fast-beam laser measurements with an estimated single-standard-deviation uncertainty of about 1%.

Core-valence correlation effects on E1 and E2 decay rates in Ca+

Knowledge of accurate oscillator strengths in neutral oxygen is of crucial importance in astrophysics. The accurate determination of the solar abundance of O I, which remains the primary sources for the entry in cosmic abundance tables, requires the use of E1 transitions appearing in the solar photospheric spectrum. A new accurate scale of oscillator strengths has therefore been obtained for the 2p 3 ( 4 S)nl-2p 3 ( 4 S)n'l' transitions of O I of astrophysical interest. Configuration interaction effects have been considered in a detailed way. The results have been used to improve the solar abundance determination for oxygen.

Accurate Oscillator Strengths of Astrophysical Interest for Neutral Oxygen

New transition probabilities based on configuration interaction wave functions, obtained in the doublet and quartet systems and for intercombination lines of neutral nitrogen, are presented. The configuration interaction calculations were performed with the CIV3 code of Hibbert A. (1975, Comp. Phys. Commun., 9). Small empirical adjustements introduced to the diagonal matrix elements achieve accurate energy splittings between the energy states. The accuracy of the transition probabilities is tested from comparisons with the most accurate theoretical or experimental results presently available. Astrophysical implications are also briefly discussed

New accurate transition probabilities for astrophysically important spectral lines of neutral nitrogen

Multiconfiguration Hartree-Fock (MCHF) calculations are presented for singlet terms in neutral strontium (Sr I) belonging to (perturbed) sp, sd, and sf Rydberg series. We discuss briefly some particularly difficult MCHF calculations and the steps taken to overcome the difficulties. The ab initio wave functions are used to calculate radiative lifetimes as well as individual transition rates for electric dipole and quadrupole radiation. The calculated lifetimes are compared to recent experimental results. The observed trends are well reproduced by the calculations. We compare our wave functions with wave functions obtained from multichannel quantum-defect theory (MQDT) in either of two different ways. One is based on semiempirical fitting to the observed energy levels and the other on a recent ab initio R-matrix calculation of MQDT parameters. We find good agreement with the wave functions obtained in the latter calculation, confirming earlier conjectures about the degree of reliability of semiempirical MQDT fits to perturbed Rydberg series (C. Froese Fischer and J. E. Hansen, Phys. Rev. A 24, 631 (1981)).

https://pure.uva.nl/ws/files/2121055/46610_214237y.pdf

Nathalie Vaeck

Papers

E1 transitions of astrophysical interest in neutral oxygen

Core-valence correlation effects on E1 and E2 decay rates in Ca+

Accurate Oscillator Strengths of Astrophysical Interest for Neutral Oxygen

New accurate transition probabilities for astrophysically important spectral lines of neutral nitrogen

Multiconfiguration Hartree-Fock calculations for singlet terms in neutral strontium.