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Rb-Rich Asymptotic Giant Branch Stars in the Magellanic Clouds
(2009-11)
We present high-resolution (R similar to 60,000) optical spectra of a carefully selected sample of heavily obscured and presumably massive O-rich asymptotic giant branch (AGB) stars in the Magellanic Clouds. We report the ...
The Chemical Compositions Of RR Lyrae Type C Variable Stars
(2014-02)
We present a detailed chemical abundance study of eight RR Lyrae variable stars of subclass c (RRc). The target RRc stars chosen for study exhibit "Blazhko-effect" period and amplitude modulations to their pulsational ...
Lithium Abundances In Nearby FGK Dwarf And Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, And Exoplanets
(2012-09)
We derive atmospheric parameters and lithium abundances for 671 stars and include our measurements in a literature compilation of 1381 dwarf and subgiant stars. First, a "lithium desert" in the effective temperature (T-eff) ...
Light-Element Abundance Variations At Low Metallicity: The Globular Cluster NGC 5466
(2010-10)
We present low-resolution (R similar or equal to 850) spectra for 67 asymptotic giant branch (AGB), horizontal branch, and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P ...
Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five R-Process-Rich, Metal-Poor Stars, and Rare Earth Lab Data Summary
(2009-05)
Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier ...
Oxygen Isotopic Ratios In Cool R Coronae Borealis Stars
(2010-05)
We investigate the relationship between R Coronae Borealis (RCB) stars and hydrogen-deficient carbon (HdC) stars by measuring precise (16)O/(18)O ratios for five cool RCB stars. The (16)O/(18)O ratios are derived by spectrum ...
Origin of Lithium Enrichment in K Giants
(2011-03)
In this Letter, we report on a low-resolution spectroscopic survey for Li-rich K giants among 2000 low-mass (M <= 3 M-circle dot) giants spanning the luminosity range from below to above the luminosity of the clump. Fifteen ...
Improved Laboratory Transition Probabilities for Er II and Application to the Erbium Abundances of the Sun and Five R-Process-Rich, Metal-Poor Stars
(2008-09)
Recent radiative lifetime measurements accurate to +/- 5% (Stockett et al. 2007, J. Phys. B 40, 4529) using laser-induced fluorescence (LIF) on 7 even-parity and 63 odd-parity levels of Er II have been combined with new ...
Light-Element Abundance Variations At Low Metallicity: The Globular Cluster NGC 5466
(2010-10)
We present low-resolution (R similar or equal to 850) spectra for 67 asymptotic giant branch (AGB), horizontal branch, and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P ...