J/ApJS/169/120 Transition probabilities for HfII and Hf (Lawler+, 2007)
Improved laboratory transition probabilities for Hf II and Hafnium abundances
in the Sun and 10 metal-poor stars.
Lawler J.E., Den Hartog E.A., Labby Z.E., Sneden C., Cowan J.J., Ivans I.I.
<Astrophys. J. Suppl. Ser., 169, 120-136 (2007)>
=2007ApJS..169..120L 2007ApJS..169..120L
ADC_Keywords: Atomic physics ; Abundances
Keywords: atomic data - Galaxy: evolution -
nuclear reactions, nucleosynthesis, abundances -
Sun: abundances - stars: individual (HD 74462, HD 115444, HD 122956,
HD 165195, HD 175305, HD 186478, HD 221170, BD +17 3248, CS 22892-052,
CS 31082-001)
Abstract:
Radiative lifetimes from laser-induced fluorescence measurements,
accurate to ~±5%, are reported for 41 odd-parity levels of HfII
(Z=72). The lifetimes are combined with branching fractions measured
using Fourier transform spectrometry to determine transition
probabilities for 150 lines of HfII. 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 lines 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
logε(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, logε(Hf/La)=-0.13±0.02 (σ=0.06) and
logε(Hf/Eu)=+0.04±0.02 (σ=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.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 55 150 Atomic transition probabilities for Hf II
organized by increasing wavelength in air
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See also:
J/A+A/377/361 : Fe II transition probabilities and loggf (Pickering+, 2001)
J/ApJS/167/292 : Laboratory transition probabilities for Gd II
(Den Hartog+, 2006)
J/ApJS/162/227 : Transition probabilities for SmII (Lawler+, 2006)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 0.1nm lambda Wavelength in air in Angstroms
10- 17 F8.2 cm-1 E1 Upper level energy
19- 21 F3.1 --- J1 Upper level J value
23- 30 F8.2 cm-1 E0 Lower level energy
32- 34 F3.1 --- J0 Lower level J value
36- 42 F7.3 10+6/s A Transition probability
44- 49 F6.3 10+6/s e_A Total uncertainty in TransP
51- 55 F5.2 --- log(gf) Log of the degeneracy times the
oscillator strength
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 17-Dec-2008