Improved Laboratory Transition Probabilities for Neutral Chromium and Redetermination of the Chromium Abundance for the Sun and Three Stars

By J. Sobeck, J. E. Lawler, C. Sneden. 2007

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Branching fraction measurements from Fourier transform spectra in conjunction with published radiative lifetimes are used to determine transition probabilities for 263 lines of neutral chromium. These laboratory values are employed to derive a new photospheric abundance for the Sun, log ϵ(Cr )☉ = 5.64 ± 0.01 (σ = 0.07). The individual Cr I solar abundances do not exhibit any trends with line strength nor with excitation energy, and there were no obvious indications of departures from LTE. In addition, oscillator strengths for singly ionized chromium recently reported by the FERRUM Project are used to determine log ϵ(Cr )☉ = 5.77 ± 0.03 (σ = 0.13). Transition probability data are also applied to the spectra of three stars: HD 75732 (metal-rich dwarf), HD 140283 (metal-poor subgiant), and CS 22892-052 (metal-poor giant). In all of the selected stars, Cr I is found to be underabundant with respect to Cr II. The possible causes for this abundance discrepancy and apparent ionization imbalance are discussed.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/937f27ad84f9e6c17990ff36ba0b37d5339def5c

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In Astronomy and Astrophysics

Citations in the corpus

NUCLEOSYNTHESIS AND EVOLUTION OF MASSIVE METAL-FREE STARS (2008, background): “It seems likely to us that there are greater uncertainties in the Cayrel et al. abundance of Cr than indicated by the published error bar (see also Cayrel et al. 2004; Sobeck et al. 2007; Lai et al. 2008).”
DETAILED CHEMICAL ABUNDANCES IN THE r-PROCESS-RICH ULTRA-FAINT DWARF GALAXY RETICULUM 2 (2016, unknown): “…et al. 2007; (3) Lawler & Dakin 1989, using HFS from Kurucz & Bell 1995; (4) Lawler et al. 2013; (5) Wood et al. 2013; (6) Lawler et al. 2014; (7) Sobeck et al. 2007; (8) Nilsson et al. 2006; (9) Booth et al. 1984; (10) Den Hartog et al. 2011 for both log gf value and HFS; (11) Ruffoni et al.…”
The elemental composition of the Sun: II. The iron group elements Sc to Ni (2014, methodology): “Based on the solar analyses by Sobeck et al. (2007) and Biémont et al. (1978), we selected the 29 best Cr i and 10 best Cr ii lines in the solar spectrum.”