The Oscillator Strengths of Fe<scp>ii</scp>λλ2507, 2509

Correge, Gwenaelle; Hibbert, A

doi:10.1086/432643

Cited by 11 publications

(25 citation statements)

References 9 publications

(16 reference statements)

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“…We have evaluated transition rates for all M1 and E2 transitions between the 100 even parity levels of 3d 6 4s, 3d 7 and 3d 5 4s 2 , as listed in the NIST tables (Ralchenko et al 2011), using both the radial functions displayed in Table 1 (set 1) and also with the radial functions we have used in previous calculations (set 2) of E1 transitions (Corrégé & Hibbert 2005). The NIST tables omit certain of the higher levels of these configurations.…”

Section: Resultsmentioning

confidence: 99%

“…In previous work on E1 transitions (for example Corrégé & Hibbert 2005), we chose the orbitals up to 4s from ground 3d 6 4s state, as given in the Hartree-Fock tabulations of Clementi & Roetti (1974), and then optimised the remaining radial functions on energies of states with 3d 6 or 3d 5 cores. In the present work, some of the main E2 or M1 transitions involve the 3d 7 states.…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…Finally, we note that we have repeated these calculations using our earlier set of radial functions (Corrégé & Hibbert 2005). These differ in the optimisation of the d-functions.…”

Section: Theoretical Methodsmentioning

confidence: 99%

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Radiative transition rates for the forbidden lines in Fe II

Deb

Hibbert

2011

A&A

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Aims. We report electric quadrupole and magnetic dipole transitions among the levels belonging to 3d 6 4s, 3d 7 and 3d 5 4s 2 configurations of Fe II in a large scale configuration interaction (CI) calculation. Methods. The CIV3 code developed by Hibbert and coworkers is used to determine configuration interaction wave functions for these levels: for the optimisation of two different sets of orbitals based on alternative choices of the 3d function, for creating and diagonalising the Hamiltonian matrices and finally for calculating transition probabilities.Results. Where possible, we have used experimental energies, not only for transition energies but also to enhance the accuracy of our ab initio CI expansions. We compare our results with those of other authors, and discuss differences between them. The good agreement between our results obtained for the same transitions but with different d-functions indicates that we have treated the state dependence of the d-functions sufficiently well. Most of our results are available in electronic form as an appendix to the paper. Conclusions. Our analysis of our own results and those of others suggests that many of our transition rates are more accurate than the rather conservative 20−30% we have stated in the text, though in a small proportion of transitions, we could not justify an accuracy greater than this.

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Section: Resultsmentioning

confidence: 99%

Section: Theoretical Methodsmentioning

confidence: 99%

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Radiative transition rates for the forbidden lines in Fe II

Deb

Hibbert

2011

A&A

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“…Here we report on a few of them which have attracted observational and laboratory interest. We have used almost the same set of optimised orbitals generated in recent calculations from our group (Corrégé & Hibbert 2005, 2006. However, we have made one change: in order to get better ab initio energy differences for the 3d 7 levels we used the Hartree-Fock (HF) 3d function given by Clementi and Roetti (1974) for 3d 7 4 F instead of their 3d of the 3d 6 4s ground configuration chosen in previous calculations (Corrégé & Hibbert 2005, 2006.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Importance of level mixing on accurate [Fe II] transition rates

Deb

Hibbert

2010

A&A

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Context. In a very recent measurement Gurell et al. (2009, A&A, 508, 525) commented that while the theoretical lifetime of a 4 G 5.5 is approximately one tenth of the lifetime of b 2 H 5.5 the corresponding measurement shows this to be close to one fifth. This large discrepancy is attributed to the effect of inadequate level mixing in the theoretical calculations. Aims. The aim of this work is to make a detailed analysis of these level mixing effects on transitions from various lower levels to the a 4 G 5.5 and b 2 H 5.5 levels given in three previous calculations and in the present more extensive CI calculation. Methods. The CIV3 structure codes of Hibbert (1975, Comput. Phys. Commun., 9, 141) and Hibbert et al. (1991, Comput. Phys. Commun., 64, 455) are used in the present work, combined with our "fine-tuning" extrapolation process.Results. The calculated mixing between the upper levels, obtained in previous calculations, is shown to be too weak. The stronger mixing determined in our work gives rise to a calculated lifetime for b 2 H 5.5 within 3% of the measured value. On the other hand our calculated lifetime for a 4 G 5.5 is around 20% lower than the measured value, which has fairly wide error bars. Conclusions. Our enhanced calculations explain the difference between previous calculations of the b 2 H 5.5 lifetime and the recent measured value and confirm the latter. We also suggest a somewhat higher value than experiment for the lifetime of a 4 G 5.5 .

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“…This modeling effort uses theoretically predicted A-values based on LS coupling (Nahar 1995). However, research by Verner et al (2002) and Correge & Hibbert (2005) show that many of the higher energy levels in Fe ii undergo configuration mixing, where assuming LS coupling can lead to predicted values differing from experimental values by several orders of magnitude. An adequate atomic model for Fe ii is crucial for deriving the correct physical conditions in the Fe ii emitting gas and predicting the Fe ii spectrum, an essential element in deriving Fe and Mg abundances based on the observed Fe ii (UV)/Mg ii ratio.…”

Section: Introductionmentioning

confidence: 97%

Modeling FeiiEmission and Revised Feii(UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

Bruhweiler

Verner

2008

ApJ

125

173

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We use the narrow-lined broad-line region ( BLR) of the Seyfert 1 galaxy, I Zw 1, as a laboratory for modeling the ultraviolet (UV ) Fe ii 2100Y3050 8 emission complex. We calculate a grid of Fe ii emission spectra representative of BLR clouds and compare them with the observed I Zw 1 spectrum. Our predicted spectrum for log n H /(cm À3 ) ½ ¼ 11:0, log È H /(cm À2 s À1 ) ½ ¼ 20:5, and /(1 km s À1 ) ¼ 20, using Cloudy and an 830 level model atom for Fe ii with energies up to 14.06 eV, gives a better fit to the UV Fe ii emission than models with fewer levels. Our analysis indicates (1) the observed UV Fe ii emission must be corrected for an underlying Fe ii pseudocontinuum; (2) Fe ii emission peaks can be misidentified as that of other ions in active galactic nuclei (AGNs) with narrow-lined BLRs possibly affecting deduced physical parameters; (3) the shape of 4200Y4700 8 Fe ii emission in I Zw 1 and other AGNs is a relative indicator of narrow-line region ( NLR) and BLR Fe ii emission; (4) predicted ratios of Ly , C iii], and Fe ii emission relative to Mg ii k2800 agree with extinction corrected observed I Zw 1 fluxes, except for C iv k1549; (5) the sensitivity of Fe ii emission strength to microturbulence casts doubt on existing relative Fe/ Mg abundances derived from Fe ii (UV)/Mg ii flux ratios. Our calculated Fe ii emission spectra, suitable for BLRs in AGNs, are available at

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The Oscillator Strengths of Feiiλλ2507, 2509

Cited by 11 publications

References 9 publications

Radiative transition rates for the forbidden lines in Fe II

Radiative transition rates for the forbidden lines in Fe II

Importance of level mixing on accurate [Fe II] transition rates

Modeling FeiiEmission and Revised Feii(UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

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