Hf Transition Probabilities and Abundances

Details Hf Transition Probabilities and Abundances Hf Transition Probabilities and Abundances

2006-11-01

arxiv.org/abs/astro-ph/0611036v1

Astronomy and Astrophysics

Astrophysics

22 pages, 6 tables, 7 figures; To be published in the Astrophysical Journal Supplement

Scientific paper

Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 150 lines of Hf II. Approximately half of these new transition probabilities overlap with recent independent measurements using a similar approach. The two sets of measurements are found to be in good agreement for measurements in common. Our new laboratory data are applied to refine the hafnium photospheric solar abundance and to determine hafnium abundances in 10 metal-poor giant stars with enhanced r-process abundances. For the Sun we derive log epsilon (Hf) = 0.88 +/- 0.08 from four lines; the uncertainty is dominated by the weakness of the lines and their blending by other spectral features. Within the uncertainties of our analysis, the r-process-rich stars possess constant Hf/La and Hf/Eu abundance ratios, log epsilon (Hf/La) = -0.13 +/- 0.02 (sigma = 0.06) and log epsilon (Hf/Eu) = +0.04 +/- 0.02 (sigma = 0.06). The observed average stellar abundance ratio of Hf/Eu and La/Eu is larger than previous estimates of the solar system r-process-only value, suggesting a somewhat larger contribution from the r-process to the production of Hf and La. The newly determined Hf values could be employed as part of the chronometer pair, Th/Hf, to determine radioactive stellar ages.

Affiliated with

Also associated with

No associations

Rating

Hf Transition Probabilities and Abundances does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Hf Transition Probabilities and Abundances, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hf Transition Probabilities and Abundances will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-291305