708 citations · 4.7k across the 48 of their papers we have counts for
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Improved Laboratory Transition Probabilities for Er II and Applications to the Erbium Abundances of the Sun and Five r-Process Rich, Metal-Poor Stars
J. E. Lawler, C. Sneden, J. J. Cowan +5
Recent radiative lifetime measurements accurate to +/- 5% (Stockett et al. 2007, J. Phys. B 40, 4529) using laser-induced fluorescence (LIF) on 8 even-parity and 62 odd-parity leve…
Europium, Samarium, and Neodymium Isotopic Fractions in Metal-Poor Stars
Ian U. Roederer, James E. Lawler, Christopher Sneden +3
We have derived isotopic fractions of europium, samarium, and neodymium in two metal-poor giants with differing neutron-capture nucleosynthetic histories. These isotopic fractions…
Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars
Jennifer S. Sobeck, James E. Lawler, Christopher Sneden
Branching fraction measurements from Fourier transform spectra in conjunction with published radiative lifetimes are used to determine transition probabilities for 263 lines of neu…
Hf Transition Probabilities and Abundances
J. E. Lawler, E. A. Den Hartog, Z. E. Labby +3
Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with b…
r-Process Enhanced Halo Stars
J. J. Cowan, C. Sneden, J. E. Lawler +1
Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight…
Gd Transition Probabilities and Abundances
E. A. Den Hartog, J. E. Lawler, C. Sneden +1
Radiative lifetimes, accurate to +/- 5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with b…
Nucleosynthesis: Stellar and Solar Abundances and Atomic Data
John J. Cowan, James E. Lawler, Christopher Sneden +2
Abundance observations indicate the presence of often surprisingly large amounts of neutron capture (i.e., s- and r-process) elements in old Galactic halo and globular cluster star…
Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars
Inese I. Ivans, Jennifer Simmerer, Christopher Sneden +4
Employing high resolution spectra obtained with the near-UV sensitive detector on the Keck I HIRES, supplemented by data obtained with the McDonald Observatory 2-d coude, we have p…
Sm Transition Probabilities and Abundances
J. E. Lawler, E. A. Den Hartog, C. Sneden +1
Radiative lifetimes, accurate to +/- 5%, have been measured for 212 odd-parity levels of Sm II using laser-induced fluorescence. The lifetimes are combined with branching fractions…
The Rise of the s-Process in the Galaxy
J. Simmerer, C. Sneden, J. J. Cowan +3
From newly-obtained high-resolution, high signal-to-noise ratio spectra the abundances of the elements La and Eu have been determined over the stellar metallicity range -3<[Fe/H]<+…
The Extremely Metal-Poor, Neutron-Capture-Rich Star CS 22892-052: A Comprehensive Abundance Analysis
C. Sneden, J. J. Cowan, J. E. Lawler +9
High-resolution spectra obtained with three ground-based facilities and the Hubble Space Telescope (HST) have been combined to produce a new abundance analysis of CS 22892-052, an…
Observations of Neutron-Capture Elements in the Early Galaxy
C. Sneden, J. J. Cowan, J. E. Lawler
Neutron-capture elements in low metallicity Galactic halo stars vary widely both in overall contents and detailed abundance patterns. This review discusses recent observational res…
The Chemical Composition and Age of the Metal-Poor Halo Star BD +17^\circ 3248
John J. Cowan, Christopher Sneden, Scott Burles +8
We have combined new high-resolution spectra obtained with the Hubble Space Telescope (HST) and ground-based facilities to make a comprehensive new abundance analysis of the metal-…
Europium Isotopic Abundances in Very Metal-poor Stars
Christopher Sneden, John J. Cowan, James E. Lawler +3
Europium isotopic abundance fractions are reported for the very metal-poor, neutron-capture-rich giant stars CS 22892-052, HD 115444, and BD +17 3248. The abundance fractions, deri…
Galactic Cosmochronometry from Radioactive Elements in the Spectra of Very Old Metal-Poor Stars
C. Sneden, J. E. Lawler, J. J. Cowan
In a short review of neutron-capture elemental abundances in Galactic halo stars, emphasis is placed on the use of these elements to estimate the age of the Galactic halo. Two prom…
Evidence of Multiple r-Process Sites in the Early Galaxy: New Observations of CS 22892-052
Christopher Sneden, John J. Cowan, Inese I. Ivans +4
First results are reported of a new abundance study of neutron-capture elements in the ultra-metal-poor (UMP; [Fe/H] = -3.1) halo field giant star CS 22892-052. Using new high reso…