Improved Laboratory Transition Probabilities for Gd II and Application to the Gadolinium Abundances of the Sun and Three r-Process Rich, Metal-poor Stars
Abstract
Radiative lifetimes, accurate to +/-5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 611 lines of Gd II. This work is the largest-scale laboratory study to date of Gd II transition probabilities and the first using a high-performance Fourier transform spectrometer. This improved data set has been used to determine a new solar photospheric Gd abundance, logɛ=1.11+/-0.03. Revised Gd abundances have also been derived for the r-process-rich metal-poor giant stars CS 22892-052, BD +17 3248, and HD 115444. The resulting Gd/Eu abundance ratios are in very good agreement with the solar system r-process ratio. We have employed the increasingly accurate stellar abundance determinations, resulting in large part from the more precise laboratory atomic data, to predict directly the solar system r-process elemental abundances for Gd, Sm, Ho, and Nd. Our analysis of the stellar data suggests slightly higher recommended values for the r-process contribution and total solar system values, consistent with the photospheric determinations, for the elements for Gd, Sm, and Ho.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- December 2006
- DOI:
- 10.1086/508262
- Bibcode:
- 2006ApJS..167..292D
- Keywords:
-
- Atomic Data;
- Stars: Abundances;
- Stars: Population II;
- Sun: Abundances