Techniques for the calculation of atomic structures and radiative data including relativistic corrections

Eissner, W.; Jones, Michael Peyton; Nussbaumer, H.

doi:10.1016/0010-4655(74)90019-8

Cited by 953 publications

(589 citation statements)

References 44 publications

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“…(c) Since previous applications of FASTWIND have concentrated on O and early B stars, we briefly note that correct treatment of cooler stars requires sufficiently well described iron group ions of stages II/III, whose lines are dominating the background opacities for these objects. Details of the corresponding model atoms and line-lists (from superstructure, Eissner et al 1974;Nussbaumer & Storey 1978, augmented by data from Kurucz 1992) can be found in Pauldrach et al (2001). In order to rule out important effects from still missing data, we have constructed an alternative dataset which uses all Fe/Ni II/III lines from the Kurucz linelist.…”

Section: Determination Of Stellar and Wind Parametersmentioning

confidence: 99%

Bright OB stars in the Galaxy

Маркова¹,

Puls²

2007

A&A

185

264

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Context. B-type supergiants represent an important phase in the evolution of massive stars. Reliable estimates of their stellar and wind parameters, however, are scarce, especially at mid and late spectral subtypes. Aims. We apply the NLTE atmosphere code FASTWIND to perform a spectroscopic study of a small sample of Galactic B-supergiants from B0 to B9. By means of the resulting data and incorporating additional datasets from alternative studies, we investigate the properties of OB-supergiants and compare our findings with theoretical predictions. Methods. Stellar and wind parameters of our sample stars are determined by line profile fitting, based on synthetic profiles, a Fourier technique to investigate the individual contributions of stellar rotation and "macro-turbulence" and an adequate approach to determine the Si abundances in parallel with micro-turbulent velocities. Results. Due to the combined effects of line-and wind-blanketing, the temperature scale of Galactic B-supergiants needs to be revised downward, by 10 to 20%, the latter value being appropriate for stronger winds. Compared to theoretical predictions, the wind properties of OB-supergiants indicate a number of discrepancies. In fair accordance with recent results, our sample indicates a gradual decrease in v ∞ over the bi-stability region, where the limits of this region are located at lower T eff than those predicted. Introducing a distance-independent quantity Q related to wind-strength, we show that this quantity is a well defined, monotonically increasing function of T eff outside this region. Inside and from hot to cool,Ṁ changes by a factor (in between 0.4 and 2.5) which is much smaller than the predicted factor of 5. Conclusions. The decrease in v ∞ over the bi-stability region is not over-compensated by an increase ofṀ , as frequently argued, provided that wind-clumping properties on both sides of this region do not differ substantially.

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Section: Determination Of Stellar and Wind Parametersmentioning

confidence: 99%

Bright OB stars in the Galaxy

Маркова¹,

Puls²

2007

A&A

185

264

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“…The importance of accurate target representation in cc calculations is to be emphasized as the necessary first step. For the cc calculations for Fe II we obtain the target eigenfunctions for Fe III using the SUPERSTRUCTURE program by Eissner et al (1974) based on a scaled Thomas-Fermi-Dirac potential and configuration interaction (CI) wave-functions. Given the number of states needed in the calculations, the atomic structure calculations are rather complicated since proper account needs to be taken of the CI effects, while the total number of configurations must be kept small to minimize, as much as possible, the memory of the CPU requirements.…”

Section: Target Statesmentioning

confidence: 99%

Atomic data for opacity calculations: XX. Photoionization cross sections and oscillator strengths for Fe II

Nahar

Pradhan

1994

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. Large scale ab initio calculations for the radiative data of Fe II have been carried out in the close coupling (cc) approbation employing the it-matrix method and a target state expansion consisting of 83 LS terms of Fe III. All bound states of Fe II with n ≤ 10 and l ≤ 7are considered. The results include 1301 bound states in LS coupling, oscillator strengths for 35 941 transitions among the bound LS states, and detailed photoionization cross sections for all bound states. Autoionizing resonances, as well as the coupling to excited core states, enhance the photoionization cross sections substantially. The calculations of oscillator strengths have been extended beyond the requirement of the Opacity Project to include a large number of fine structure transitions in Fe II, using an algebraic transformation of the LS coupled line strength and the observed energies. The present ƒ-values compare favourably with available experimental values and the calculations by Kurucz. However, the present results differ considerably from earlier 16-state R-matrix calculations and the new radiative data yield Rosseland mean opacities that are 50% higher. Some special features in the monochromatic opacity spectra of Fe II are also noted.

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“…Some of the discrepancies noted by Brickhouse et al and Young, Landi & Thomas (1998) were later resolved by Storey et al (2000), who also performed a large collisional calculation among the lowest 40 levels of the 3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 and 3s3p3d configurations. For the determination of energy levels and radiative rates, they adopted the SuperStructure (SS) code of Eissner, Jones & Nussbaumer (1974), and for the scattering process the R-matrix code of Berrington et al (1978) was used. The calculations were basically performed in the LS coupling (Russell-Saunders or spin-orbit coupling), but mass and Darwin relativistic energy shifts were included through the term coupling coefficients while transforming the LS coupling reactance matrices to the intermediate coupling scheme.…”

Section: Introductionmentioning

confidence: 99%

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Aggarwal

Keenan

2014

Monthly Notices of the Royal Astronomical Society

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Energies and lifetimes are reported for the lowest 136 levels of Fe XIV, belonging to the (1s 2 2s 2 2p 6 ) 3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 , 3s3p3d, 3p 2 3d, 3s3d 2 , 3p3d 2 and 3s 2 4 configurations. Additionally, radiative rates, oscillator strengths and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions. Theoretical lifetimes determined from these radiative rates for most levels show satisfactory agreement with earlier calculations, as well as with measurements. Electron impact excitation collision strengths are also calculated with the Dirac atomic R-matrix code (DARC) over a wide energy range up to 260 Ryd. Furthermore, resonances have been resolved in a fine energy mesh to determine effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities. Results are listed for all 9180 transitions among the 136 levels over a wide range of electron temperatures, up to 10 7.1 K. Comparisons are made with available results in the literature, and the accuracy of the present data is assessed.

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Techniques for the calculation of atomic structures and radiative data including relativistic corrections

Cited by 953 publications

References 44 publications

Bright OB stars in the Galaxy

Bright OB stars in the Galaxy

Atomic data for opacity calculations: XX. Photoionization cross sections and oscillator strengths for Fe II

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

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