Improved V II Log(gf) Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-Poor Star HD 84937

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Date

2014-10

Authors

Wood, M. P.
Lawler, James E.
Den Hartog, E. A.
Sneden, Christopher
Cowan, John J.

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Abstract

New experimental absolute atomic transition probabilities are reported for 203 lines of VII. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported VII transition probabilities. Two spectrometers, independent radiometric calibration methods, and independent data analysis routines enable a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new VII data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log epsilon(V) = 3.95 from 15 VII lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H]= -2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.

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Wood, M. P., J. E. Lawler, E. A. Den Hartog, C. Sneden, and J. J. Cowan. "Improved V II log (gf) Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937." The Astrophysical Journal Supplement Series, Vol. 214, No. 2 (Oct., 2014): 18.