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D.J. Bord (UMich-Dearborn)
The third spectra of lanthanide rare-earth elements are frequently identified in high resolution, high signal-to-noise spectroscopic data for stars whose chemistry differs significantly from that of the Sun. The availability of reliable atomic data for such species, particularly radiative lifetimes and transition probabilities, is quite limited, making accurate abundance estimates based on these ions difficult to achieve. We report here the first theoretical calculations of oscillator strengths and Landé g-factors for the rare-earth ions Nd III and Pr III. The methodology employs the Cowan code, and emphasis is placed on strong transitions in the optical region of the spectrum, although some information is available for Pr III for wavelengths shorter than 3000 Å. Comparisons of prior ab initio calculations of this type that we have made for other lanthanides (for example, La II, Ce III, and Lu II) with published experimental and theoretical data suggest that the expected accuracy of the new log(gf) values for individual transitions is about ±0.15 dex in the absence of significant core polarization effects. The g-factors should be good to better than 5% on average, except in a few cases where term mixing is important. Applications of the data are made in the computation of neodymium and praseodymium abundances in the atmospheres of several chemically peculiar stars, including HD101065 and HD122970.