New radiative lifetime measurements using time-resolved laser-induced Ñuorescence are reported for the lowest six even-parity levels of Eu II. Branching fractions, measured from Fourier transform spectra, are combined with these lifetimes to determine atomic transition probabilities for the strongest blueÈUV lines and additional yellowÈred lines of Eu II. These results are compared with published data, and generally good agreement is found. Recommended hyperÐne structure constants and isotopic shifts for these lines are also assembled from the literature and supplemented, as needed, using results from nonlinear least-squares Ðts of line proÐles in Fourier transform spectra. These laboratory data are applied in a new determination of the solar Eu elemental abundance, yielding with^0.04 Slog 10 e(Eu)T \ 0.52^0.01, estimated for each of internal (scatter) and external (systematic) uncertainties. From analysis of the proÐles of three Eu II lines, primarily j4129, isotopic fractions of 151Eu and 153Eu are shown to be consistent with their values in meteoritic material.

We have derived new very accurate abundances of the Fe-group elements Sc through Zn (Z = 21−30) in the bright main-sequence turnoff star HD 84937, based on high-resolution spectra covering the visible and ultraviolet spectral regions. New or recent laboratory transition data for 14 species of seven elements have been used. Abundances from more than 600 lines of non-Fe species have been combined with about 550 Fe lines in HD 84937 to yield abundance ratios of high precision. The abundances have been determined from both neutral and ionized transitions, which generally are in agreement with each other. We find no substantial departures from standard LTE Saha ionization balance in this [Fe/H] = −2.32 star. Noteworthy among the abundances are: [Co/Fe] = +0.14 and [Cu/Fe] = −0.83, in agreement with past studies abundance trends in this and other low metallicity stars; and [Sc,Ti,V/Fe] = +0.31, which has not been noted previously. A detailed examination of scandium, titanium, and vanadium abundances in large-sample spectroscopic surveys reveals that they are positively correlated in stars with [Fe/H] < −2; HD 84937 lies at the high end of this correlation. These trends constrain the synthesis mechanisms of Fe-group elements. We also examine the GCE abundance trends of the Fe-group elements, including a new nucleosynthesis model with jet-like explosion effects.

We have derived new abundances of the rare-earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally-consistent Ba, rare-earth, and Hf (56 ≤ Z ≤ 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

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Radiative lifetimes, accurate to AE5%, have been measured for 212 odd-parity levels of Sm ii using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for more than 900 lines of Sm ii. This work is the largest scale laboratory study to date of Sm ii transition probabilities using modern methods. This improved data set has been used to determine a new solar photospheric Sm abundance, log ¼ 1:00 AE 0:03, from 26 lines. The spectra of three very metal-poor, neutroncapture-rich stars also have been analyzed, employing between 55 and 72 Sm ii lines per star. The abundance ratios of Sm relative to other rare earth elements in these stars are in agreement and are consistent with ratios expected from rapid neutron-capture nucleosynthesis (the r-process).