Fe II lifetimes and transition probabilities

Schnabel, R.; Schultz-Johanning, M.; Kock, M.

doi:10.1051/0004-6361:20031685

Cited by 39 publications

(40 citation statements)

References 16 publications

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“…Fe  oscillator strengths increased in accuracy over the past 20 years as progressively more accurate TRLIF lifetimes were measured by Hannaford et al (1992), Schnabel et al (1999) and Schnabel et al (2004), and used to normalise earlier FTS and grating spectrometer emission BFs from Heise & Kock (1990) and Kroll & Kock (1987). Probably the most accurate g f -values now come from the compilation of , who used these and other experimental lifetimes to recalibrate and average a raft of theoretical and experimental BFs; we adopt these data for all our Fe  lines.…”

Section: Oscillator Strengthsmentioning

confidence: 91%

The elemental composition of the Sun

Scott

Asplund

Grevesse

et al. 2014

A&A

265

202

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We redetermine the abundances of all iron group nuclei in the Sun, based on neutral and singly-ionised lines of Sc, Ti, V, Mn, Fe, Co and Ni in the solar spectrum. We employ a realistic 3D hydrodynamic model solar atmosphere, corrections for departures from local thermodynamic equilibrium (NLTE), stringent line selection procedures and high quality observational data. We have scoured the literature for the best quality oscillator strengths, hyperfine constants and isotopic separations available for our chosen lines. We find log Sc = 3.16 ± 0.04, log Ti = 4.93 ± 0.04, log V = 3.89 ± 0.08, log Cr = 5.62 ± 0.04, log Mn = 5.42 ± 0.04, log Fe = 7.47 ± 0.04, log Co = 4.93 ± 0.05 and log Ni = 6.20 ± 0.04. Our uncertainties factor in both statistical and systematic errors (the latter estimated for possible errors in the model atmospheres and NLTE line formation). The new abundances are generally in good agreement with the CI meteoritic abundances but with some notable exceptions. This analysis constitutes both a full exposition and a slight update of the preliminary results we presented in Asplund et al. (2009, ARA&A, 47, 481), including full line lists and details of all input data we employed.

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Section: Oscillator Strengthsmentioning

confidence: 91%

The elemental composition of the Sun

Scott

Asplund

Grevesse

et al. 2014

A&A

265

202

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“…Unfortunately, these groups did not provide data for some Fe i lines that are important for the stellar iron spectrum analysis. Five sets of oscillator strengths from Meléndez & Barbuy (2009);Moity (1983); Raassen & Uylings (1998);Schnabel et al (2004), and the vald database (Kupka et al 1999) were inspected for Fe ii. We found that the solar mean abundance derived from the Fe ii lines varies between log ε = 7.41 ± 0.11 and log ε = 7.56 ± 0.05 depending on the source of g f -values (Table 1).…”

Section: Line Selection and Atomic Datamentioning

confidence: 99%

A non-LTE study of neutral and singly-ionized iron line spectra in 1D models of the Sun and selected late-type stars

Mashonkina

Gehren

Shi

et al. 2011

A&A

231

266

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Aims. We evaluate non-local thermodynamical equilibrium (non-LTE) line formation for the two ions of iron and check the ionization equilibrium between Fe i and Fe ii in model atmospheres of the cool reference stars based on the best available complete model atom for neutral and singly-ionized iron.Methods. We present a comprehensive model atom for Fe with more than 3000 measured and predicted energy levels. As a test and first application of the improved model atom, iron abundances are determined for the Sun and five stars with well determined stellar parameters and high-quality observed spectra. The efficiency of inelastic collisions with hydrogen atoms in the statistical equilibrium of iron is empirically estimated from inspection of their different influence on the Fe i and Fe ii lines in the selected stars. Results. Non-LTE leads to systematically depleted total absorption in the Fe i lines and to positive abundance corrections in agreement with the previous studies, however, the magnitude of such corrections is smaller compared to the earlier results. These non-LTE corrections do not exceed 0.1 dex for the solar metallicity and mildly metal-deficient stars, and they vary within 0.21 dex and 0.35 dex in the very metal-poor stars HD 84937 and HD 122563, respectively, depending on the assumed efficiency of collisions with hydrogen atoms. Based on the analysis of the Fe i/Fe ii ionization equilibrium in these two stars, we recommend to apply the Drawin formalism in non-LTE studies of Fe with a scaling factor of 0.1. For the Fe ii lines non-LTE corrections do not exceed 0.01 dex in absolute value over the whole range of stellar parameters that are considered. This study reveals two problems. The first one is that g f -values available for the Fe i and Fe ii lines are not accurate enough to pursue high-accuracy absolute stellar abundance determinations. For the Sun, the mean non-LTE abundance obtained from 54 Fe i lines is 7.56 ± 0.09 and the mean abundance from 18 Fe ii lines varies between 7.41 ± 0.11 and 7.56 ± 0.05 depending on the source of the g f -values. The second problem is that lines of Fe i give, on average, a 0.1 dex lower abundance compared with those of Fe ii lines for HD 61421 and HD 102870, even when applying a differential line-by-line analysis with regard to the Sun. A disparity between neutral atoms and first ions points to problems of stellar atmosphere modelling or/and effective temperature determination.

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“…Those data were calibrated with the following experimental data: lifetimes of upper levels from Schnabel et al (2004), Schnabel et al (1999), Schnabel & Kock (2001), Guo et al (1992), Hannaford et al (1992), and Biémont et al (1991), and branching fractions by , Pauls et al (1990), and Kroll & Kock (1987). The (absorption) oscillator strength f lu is related to the branching fraction (BF lu ) and the lifetime (τ u ) by (e.g.…”

Section: Improved Oscillator Strengthsmentioning

confidence: 99%

“…The g f -values given by Schnabel et al (2004) for lines used in the solar iron abundance determination are very similar to those given in Schnabel et al (1999), and indeed the result given by Schnabel et al (2004) is the same (both in the mean value and line-to-line scatter) as in Schnabel et al (1999), A Fe = 7.42 (σ = 0.09); therefore, the revised values given by Schnabel et al (2004) do not improve the precision of their older transition probabilities. The g f -values given in the critical compilation of Fuhr & Wiese (2006) in the optical region are mainly based on the laboratory results of Schnabel et al (2004), which are not very precise as discussed above, and the (uncorrected) theoretical results of Raassen & Uylings (1998), which are not very accurate.…”

Section: The Solar Iron Abundancementioning

confidence: 99%

Both accurate and precisegf-values for Fe II lines

Meléndez¹,

Barbuy

2009

A&A

162

145

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We present a new set of oscillator strengths for 142 Fe ii lines in the wavelength range 4000-8000 Å. Our g f -values are both accurate and precise, because each multiplet was globally normalized using laboratory data (accuracy), while the relative g f -values of individual lines within a given multiplet were obtained from theoretical calculations (precision). Our line list was tested with the Sun and high-resolution (R ≈ 10 5 ), high-S/N (≈700-900) Keck+HIRES spectra of the metal-poor stars HD 148816 and HD 140283, for which line-to-line scatter (σ) in the iron abundances from Fe ii lines as low as 0.03, 0.04, and 0.05 dex are found, respectively. For these three stars the standard error in the mean iron abundance from Fe ii lines is negligible (σ mean ≤ 0.01 dex). The mean solar iron abundance obtained using our g f -values and different model atmospheres is A Fe = 7.45(σ = 0.02).

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Fe II lifetimes and transition probabilities

Cited by 39 publications

References 16 publications

The elemental composition of the Sun

The elemental composition of the Sun

A non-LTE study of neutral and singly-ionized iron line spectra in 1D models of the Sun and selected late-type stars

Both accurate and precisegf-values for Fe II lines

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