Lifetimes, transition probabilities, and level energies in Fe i

O’Brian, Thomas R.; Wickliffe, M. E.; Lawler, J. E.; Whaling, Ward; Brault, J. W.

doi:10.1364/josab.8.001185

Cited by 322 publications

(166 citation statements)

References 20 publications

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“…Multiple literature sources give a transition probability for the 6027Å feature. The emission measurement technique of O'Brian et al (1991) yielded a gf-value for the 6027Å line that is in good agreement with that found by the absorption line technique of Blackwell et al (1982) . We adopted the O'Brian et al log (gf) value for this line.…”

Section: Line Parameterssupporting

confidence: 82%

“…Unfortunately, neither O'Brian et al (1991) nor Blackwell et al (1982) give a transition probability for the 6024Å feature. Literature sources for this line include the early work of Wolnik et al (1970), log (gf)= −0.06±0.00 ; the solar line inversion value of Thévenin (1990), log (gf)= −0.02±0.02; and the semi-empirical derivation of Kurucz (1993), log (gf)= −0.120.…”

Section: Line Parametersmentioning

confidence: 99%

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Manganese abundances in cluster and field stars

et al. 2005

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We have derived Mn abundances for more than 200 stars in 19 globular clusters. In addition, Mn abundance determinations have been made for a comparable number of halo field and disk stars possessing an overlapping range of metallicities and stellar parameters. Our primary data set was comprised of high resolution spectra previously acquired at the McDonald, Lick and Keck Observatories. To enlarge our data pool, we acquired globular and open cluster spectra from several other investigators. Data were analyzed using synthetic spectra of the 6000Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. Our analysis shows that for the metallicity range −0.7>[Fe/H]>−2.7 stars of 19 globular clusters have a a mean relative abundance of <[Mn/Fe]>= −0.37 ± 0.01 (σ = 0.10), a value in agreement with that of the field stars: <[Mn/Fe]>= −0.36 ± 0.01 (σ = 0.08). Despite the 2 orders of magnitude span in metallicity, the <[Mn/Fe]> ratio remains constant in both stellar populations. Our Mn abundance data indicate that there is no appreciable variation in the relative nucleosynthetic contribution from massive stars that undergo core-collapse supernovae and thus, no significant change of the associated initial mass function in the specified metallicity range.

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Section: Line Parameterssupporting

confidence: 82%

Section: Line Parametersmentioning

confidence: 99%

Manganese abundances in cluster and field stars

et al. 2005

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“…Transition probabilities for the Fe i lines were obtained from several laboratory experiments, including studies of Fe i absorption lines produced by iron vapor in a carbon tube furnace (Blackwell, Petford, & Shallis 1979;Blackwell, Petford, & Simmons 1982b;Blackwell et al 1982aBlackwell et al , 1986 [Oxford Group]), measurement of radiative lifetimes of Fe i transitions by laser induced fluorescence (O'Brian et al 1991;Bard & Kock 1994), Fe i emission-line spectroscopy from a low current arc (May, Richter, & Wichelmann 1974), and emission lines of Fe i from a shock tube (Wolnik, Berthel, & Wares 1971). We also considered solar gf-values from Thévenin (1989Thévenin ( , 1990 when needed.…”

Section: Transition Probabilitiesmentioning

confidence: 99%

“…We also considered solar gf-values from Thévenin (1989Thévenin ( , 1990 when needed. The Fe i gf-values obtained by the different experiments were placed on a common scale with respect to the results from O'Brian et al (1991;see Ramírez et al 2001 for details). The gf-values for our Fe ii lines were taken from the solar analysis of Blackwell, Shallis, & Simmons (1980), Biémont et al (1991), and the semiempirical calculations of Kurucz (1993b).…”

Section: Transition Probabilitiesmentioning

confidence: 99%

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Ramírez

Cohen

2003

The Astronomical Journal

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We present the iron abundance and abundance ratios for 18 elements with respect to Fe in a sample of stars with a wide range in luminosity, from luminous giants to stars near the turnoff in the globular cluster M5. The analyzed spectra, obtained with the High Resolution Echelle Spectrograph at the Keck Observatory, are of high dispersion (R = /D = 35,000). We find that the neutron capture, the iron peak, and the -element abundance ratios show no trend with T eff and low scatter around the mean between the top of the red giant branch and near the main-sequence turnoff, suggesting that at this metallicity non-LTE effects are not important over the range of stellar parameters spanned by our sample. To within the precision of the measurements (about AE0.1 dex), gravitationally induced heavy-element diffusion does not appear to be present among the stars near the main-sequence turnoff studied here. Our work and other recent studies suggest that heavy-element diffusion is inhibited in the surface layers of metal-poor stars. Differences in the Na abundance from star to star that extend to the main-sequence turnoff are detected in our sample in M5. The anticorrelation between O and Na abundances, observed in other metal-poor globular clusters, is not detected in our sample, but it may be hidden among stars with only upper limits for their O abundances. As we found in M71, there is a hint of star-to-star variation in the Zr abundance. Overall the abundance ratios of M5 appear very similar to those of M71, with the possible exception of the neutron capture element Ba, for which we argue that the apparent difference may be due to difficulties in the analysis. As in M71, the -elements Mg, Ca, Si, and Ti are overabundant relative to Fe. The results of our abundance analysis of 25 stars in M5 provide further evidence of abundance variations among specific light elements at unexpectedly low luminosities, which cannot be explained by our current understanding of stellar evolution.

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“…A log (g f )value can be calculated for the Y ii line at 4177.536 8 from the f-value in Hannaford et al (1982), and a log (g f ) value for the Fe i line at 4177.5935 8 is given in O'Brian et al (1991). This blend is easily accounted for and has little effect on the derived Nd isotopic fraction.…”

Section: A3 Neodymium Linesmentioning

confidence: 99%

Europium, Samarium, and Neodymium Isotopic Fractions in Metal‐Poor Stars

Roederer¹,

Lawler²,

Sneden³

et al. 2008

AIP Conference Proceedings

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We have derived isotopic fractions of europium, samarium, and neodymium in two metal-poor giants with differing neutron-capture nucleosynthetic histories. These isotopic fractions were measured from new high-resolution (R $ 120;000), high signal-to-noise ratio (S/N $ 160Y1000) spectra obtained with the 2d-coudé spectrograph of McDonald Observatory's 2.7 m Smith telescope. Synthetic spectra were generated using recent high-precision laboratory measurements of hyperfine and isotopic subcomponents of several transitions of these elements and matched quantitatively to the observed spectra. We interpret our isotopic fractions by the nucleosynthesis predictions of the stellar model, which reproduces s-process nucleosynthesis from the physical conditions expected in low-mass, thermally pulsing stars on the AGB, and the classical method, which approximates s-process nucleosynthesis by a steady neutron flux impinging on Fe-peak seed nuclei. Our Eu isotopic fraction in HD 175305 is consistent with an r-process origin by the classical method and is consistent with either an r-or an s-process origin by the stellar model. Our Sm isotopic fraction in HD 175305 suggests a predominantly r-process origin, and our Sm isotopic fraction in HD 196944 is consistent with an s-process origin. The Nd isotopic fractions, while consistent with either r-process or s-process origins, have very little ability to distinguish between any physical values for the isotopic fraction in either star. This study for the first time extends the n-capture origin of multiple rare earths in metal-poor stars from elemental abundances to the isotopic level, strengthening the r-process interpretation for HD 175305 and the s-process interpretation for HD 196944.

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Lifetimes, transition probabilities, and level energies in Fe i

Cited by 322 publications

References 20 publications

Manganese abundances in cluster and field stars

Manganese abundances in cluster and field stars

Abundances in Stars from the Red Giant Branch Tip to near the Main-Sequence Turnoff in M5

Europium, Samarium, and Neodymium Isotopic Fractions in Metal‐Poor Stars

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