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The dependence of the Rosseland Mean Opacity (RMO) on the equation of state and the number of included atomic levels of iron ions prevalent at the solar radiative/convection boundary is investigated. The 'chemical picture' Mihalas–Hummer–Däppen (MHD) equation-of-state (EOS), and its variant QMHD–EOS, are studied at two representative temperature–density sets at the base of the convection zone and the Sandia Z experiment: (2 × 106 K, 1023/cc) and (2.11 × 106 K, 3.16 × 1022/cc), respectively. It is found that whereas the new atomic data sets from accurate R-matrix calculations for opacities (RMOP) are vastly overcomplete, involving hundreds to over a thousand levels of each of the three Fe ions considered – Fe  xvii , Fe  xviii , Fe  xix – the EOS constrains contributions to RMOs by relatively fewer levels. The RMOP iron opacity spectrum is quite different from the Opacity Project distorted wave model and shows considerably more plasma broadening effects. This work points to possible improvements needed in the EOS for opacities in high-energy–density plasma sources. [ABSTRACT FROM AUTHOR]

1983: 1 14 Berrington K.A., Eissner W.B., Saraph H.E., Seaton M.J., Storey P.J. A comparison of close-coupling calculations using UCL and QUB codes. Werner Eissner (Figure 1), a pioneer in computational atomic physics, was born on 16 October 1930 in the city of Görlitz, Germany, to Bernhard and Frieda (née Eckert) Eissner. Werner therefore relocated to DL in March 1980 and, then, in 1985, to the QUB Department of Applied Mathematics and Theoretical Physics, as Professor Burke's appointment there became full-time in 1982 and, by 1985, he had negotiated Werner's transfer. One of us (AKB) reminisces about Werner's collaboration at GSFC [[22]]: In 1974, I met Werner while spending a few days at University College London learning how to use the superstructure and Distorted Wave codes. [Extracted from the article]

Platinum compounds, such as cisplatin and other high-Z materials, are increasingly common in biomedical applications. The absorption and emission of high-energy X-rays can occur via the 1s-2p [K.sub.α] transitions in ions of heavy elements involving deep inner-shells. Oscillator strengths (f), line strengths (S), and radiative decay rates (A), for the 1s-2p transitions for the nine ionic states from hydrogen-like to fluorine-like, are presented for platinum and uranium. For platinum ions the [K.sub.α] transitions are found to be in the hard X-ray region, 64-71 keV (0.18-0.17 Å), and for uranium ions they are in the range 94-105 keV (0.12-0.13 Å). Since the number of electrons in each ionic state of the element is different, the number of [K.sub.α] transitions varies considerably. While there are two 1s-2p transitions (1s ²[S.sub.1/2]-2p ²[P[.sup.o.sub.1/2,3/2]) in H-like ions, there are 2, 6, 2, 14, 35, 35, and 14 transitions in He-like, Li-like, Be- like, B-like, C-like, N-like, and O-like ions, respectively, for a total of 112 [K.sub.α] transitions for each element. These include both types of electric dipole (E1) allowed transitions, same-spin multiplicity and intercombination. The former dipole allowed transitions are in general strong; their radiative decay rates are of the order of A ~ [10.sup.16][s.sup.-1]. However, there are also many weaker transitions. We demonstrate the importance of these [K.sub.α] transitions, as they appear as resonances in photo- ionization, which is relevant to the enhanced production of Auger electrons for possible radiation diagnostics and therapy. PACS Nos: 32.80.-t, 32.80.Fb, 33.60.+q Les composes de platine comme le cisplatine et d'autres composes d'elements de Z eleve sont de plus en plus utilises dans les applications biomedicales. L'absorption et remission de rayons-X de haute energie peuvent se produire via les transitions 1s-2p [K.sub.α], impliquant les couches internes dans les ions d'elements lourds. Nous presentons ici, pour les ions de platine et d'uranium, les forces d'oscillateur (f), les intensites de raie (S) et les taux de desintegration (A) des transitions 1s-2p pour les neuf etats ioniques qui vont du type hydrogene jusqu'au type fluor. Pour les ions de platine, les transitions [K.sub.α] sont dans la region des rayons-X durs, 64-71 keV (0,18-0,17 Å) et pour l'uranium, dans la region 94-105 keV (0,120,13 Å). Parce que le nombre d' electrons dans chaque etat ionique des deux elements est different, le nombre de transitions [K.sub.α] varie considerablement. Alors qu'il y a deux transitions 1s-2p (1s ²[S.sub.1/2]- 2p ²[P[.sup.o.sub.1/2,3/2]) dans les ions de type H, il y a 2, 6, 2, 14, 35, 35 et 14 transitions dans les ions de type He, Li, Be, B, C, N, et O respectivement, pour un total de 112 transitions [K.sub.α] pour chaque element. Elles incluent les deux sortes de transitions E1 permises : meme multiplicite de spin et intercombinaison. Les transitions permises des premieres sont intenses et leur taux de desintegration est de l'ordre de A ~ [10.sup.16][s.sup.-1]. Cependant, il y a aussi des transitions moins intenses. Nous demontrons l'importance de ces dernieres transitions [K.sub.α] qui apparaissent comme des resonances dans la photoionisation et sont importantes, parce qu'elles augmentent la production d' electrons Auger, qui peuvent etre utiles dans le diagnostique et la therapie par radiation. [Traduit par la Redaction], 1. Introduction In previous works [1-4], a new methodology called resonant theranostics has been proposed, employing resonant X-ray irradiation of high-Z materials for potential usage as diag nostic and therapeutic [...]

Phosphorus abundance is crucial for DNA-based extraterrestrial life in exoplanets. Atomic data for observed spectral lines of P-ions are needed for its accurate determination. We present the first calculations for collision strengths for the forbidden [P  iii ] fine structure transition $$\mathrm{ 3s^23p (^2P^o_{1/2{\text{--}}3/2})}$$ within the ground state at 17.9 $$\mu$$ m , as well as allowed UV transitions in the $$\mathrm{ 3s^23p (^2P^o_{1/2,3/2}) \rightarrow 3s3p^2 (^2D_{3/2,5/2}, ^2S_{1/2}, ^2P_{1/2,3/2})}$$ multiplets between 915 and 1345 Å. Collision strengths are computed using the Breit–Pauli R-Matrix method including the first 18 levels, and they exhibit extensive auto-ionizing resonance structures. In particular, the Maxwellian averaged effective collision strength for the FIR 17.9 $$\mu$$ m  transition shows a factor 3 temperature variation broadly peaking at typical nebular temperatures. Its theoretical emissivity with solar phosphorus abundance is computed relative to H β and found to be similar to observed intensities from planetary nebulae; the abundances derived in earlier works are 3–5 times sub-solar. The results pertain to the reported paucity of phosphorus from preferred production sites in supernovae, and abundances in planetary nebulae and supernova remnants. [ABSTRACT FROM AUTHOR]

ABSTRACT Far-infrared and optical [O iii] lines are useful temperature-density diagnostics of nebular as well as dust obscured astrophysical sources. Fine-structure transitions among the ground state levels 1 s22 s22 p33 P 0,1,2 give rise to the 52- and 88-m lines, whereas transitions among the 3 P 0,1,2, 1 D 2, 1 S 0 levels yield the well-known optical lines λλ4363, 4959 and 5007 Å. These lines are excited primarily by electron impact excitation. However, despite their importance in nebular diagnostics collision strengths for the associated fine-structure transitions have not been computed taking full account of relativistic effects. We present Breit-Pauli R-matrix calculations for the collision strengths with highly resolved resonance structures. We find significant differences of up to 20 per cent in the Maxwellian averaged rate coefficients from previous works. We also tabulate these to lower temperatures down to 100 K to enable determination of physical conditions in cold dusty environments such photodissociation regions and ultraluminous infrared galaxies observed with the Herschel Space Observatory. We also examine the effect of improved collision strengths on temperature- and density-sensitive line ratios. [ABSTRACT FROM AUTHOR]

Time-dependent numerical simulations of the Kα complex of Fe xxvare carried out as a function of temperature–density–radiation field variations in high-temperature astrophysical and laboratory plasmas. In addition to several well-known features, the transient and steady-state spectra reveal the effects due to (a) time-dependent thermal and non-thermal radiation fields, (b) photo- and collisional excitation and ionization, and (c) high densities, on the‘quartet’ of principallines, and dielectronic satellites. The highly detailed models show precisely how, assuming a temporal–temperature correlation, the X-ray intensity varies between 6.6 and 6.7 keV and undergoes a‘spectral inversion’ in thewandzline intensities, characterizing an ionization- or a recombination-dominated plasma. The dielectronic satellite intensities are the most temperature-dependent features, but insensitive to density variations, and significantly contribute to the Kα complex forleading to asymmetric profiles. The 6.7-keV Kα complex should be a potential diagnostic of X-ray flares in active galactic nuclei, afterglows in gamma-ray bursts, and other non-equilibrium sources with the high-resolution measurements possible from the upcoming missionAstro-E2. It is also shown that high electron densities attenuate the line intensities in simulations relevant to laboratory plasmas, such as in inertial confinement fusion, laser, or magnetic Z-pinch devices. [ABSTRACT FROM AUTHOR]

Near-infrared spectroscopic observations in the range 0.8-2.4¼m are used to study the kinematics and excitation mechanisms of Molecular Hydrogen and [FeII] lines in a sample of AGNs. The width of H2 lines is narrower than [FeII] lines, therefore they do not originate from the same parcel of gas. The molecular emission is found to be purely thermal but with heating processes which vary among the objects. A clear correlation between H2/Br³ and [FeII] 1.257¼m/Pa² is found for our sample objects supplemented with data from the literature. The correlation of these line ratios is a useful diagnostic tool in the NIR to separate emitting line objects by their level of nuclear activity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html [ABSTRACT FROM PUBLISHER]

ABSTRACT The Kα resonance complexes in oxygen ions O i–O viare theoretically computed, and resonance oscillator strengths and wavelengths are presented. The highly resolved photoionization cross-sections, with relativistic fine structure, are computed in the coupled channel approximation using the Breit–Pauli R-matrix method. A number of strong Kα resonances are found to be appreciable, with resonance oscillator strengths f[sub r] > 0.1 . The Kα resonance wavelengths of O i–O vilie in the relatively narrow wavelength range 22–23.5 Å, and the X-ray opacity in this region should therefore be significantly affected by K → L transitions in oxygen. The results should be useful in the interpretation of soft X-ray spectra observed from Chandra and XMM–Newton. [ABSTRACT FROM AUTHOR]

Asserts the domination of dielectronic satellites (DES) to the X-ray spectral formation in the 607-keV Kα complex of Fexxv. Definitions of diagnostic line ratio, DES and the lines with parameters from new relativistic atomic calculations; Source of the DES absorption resonance strengths from differential oscillator strengths; Assertion of the DES contribution to highly ionized iron.