Lifetime Measurements in La II with the Beam-Laser Method

Arnesen, A.; Bengtsson, A.; Hallin, R.; Lindskog, J.; Nordling, C.; Noreland, T.

doi:10.1088/0031-8949/16/1-2/004

Cited by 33 publications

(13 citation statements)

References 17 publications

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“…The impressive level of agreement among various LIF experiments is evident in this table. The LIF lifetime measurements by Arnesen et al (1977aArnesen et al ( , 1977b and by Li & Zhankui (1999) are in agreement with ours in all but one case. The average and rms percent di †erences between the previous LIF lifetime measurements and our measurements are ]3.2% and 6.4%, respectively.…”

Section: Radiative Lifetime Measurementssupporting

confidence: 89%

Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths for Laiiand a New Determination of the Solar Lanthanum Abundance

Lawler

Bonvallet

Sneden

2001

ApJ

324

263

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Radiative lifetimes, accurate in most cases to^5%, from time-resolved laser-induced Ñuorescence measurements on a slow beam of lanthanum ions are reported for 31 odd-parity levels of La II. Experimental branching fractions for La II from emission spectra covering the near-ultraviolet to the nearinfrared are also reported. The spectra were recorded using the US National Solar Observatory 1.0 m Fourier transform spectrometer. The branching fractions are combined with the radiative lifetimes to produce 84 experimentally determined transition probabilities or oscillator strengths, generally accurate to^10%, for La II. These new experimental results are compared to older experimental and theoretical results. These data are applied to determine a new value for the solar photospheric lanthanum abundance, with estimated internal errors of^0.03 and external errors of^0.03. Slog 10 v(La)T \ 1.13,

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Section: Radiative Lifetime Measurementssupporting

confidence: 89%

Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths for Laiiand a New Determination of the Solar Lanthanum Abundance

Lawler

Bonvallet

Sneden

2001

ApJ

324

263

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“…There are no gf-values in NIST for these lines. We were forced to use the transition probabilities from Corliss & Bozman (1962), adjusted as recommended by Arneson et al (1977), for the three La ii lines. Since the submission of our M71 paper, a new analysis of the spectrum of La ii has appeared.…”

Section: Solar Abundancesmentioning

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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“…If the overabundance factors of the lanthanides in typical magnetic Ap stars resemble those in the Am's, we may use Hundt's (1972) Andersen et al (1975) and Arnesen et al (1977), and obtain an excess of 2.1 dex.…”

Section: Synthesismentioning

confidence: 99%

Rare-earth systematics in Ap and Am stellar spectra: Are new theoretical developments required?

Cowley

1980

Vistas in Astronomy

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Lifetime Measurements in La II with the Beam-Laser Method

Cited by 33 publications

References 17 publications

Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths for Laiiand a New Determination of the Solar Lanthanum Abundance

Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths for Laiiand a New Determination of the Solar Lanthanum Abundance

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

Rare-earth systematics in Ap and Am stellar spectra: Are new theoretical developments required?

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