Reference : Transition probabilities of astrophysican interest in the niobium ions (Nb II and Nb III)
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/2268/80611
Transition probabilities of astrophysican interest in the niobium ions (Nb II and Nb III)
English
Nilsson, H. [> >]
Hartman, H. [> >]
Engström, L. [> >]
Lundberg, H. [> >]
Sneden, C. [> >]
Fivet, V. [> >]
Palmeri, P. [> >]
Quinet, Pascal mailto [Université de Liège - ULg > Département de physique > Physique nucléaire, atomique et spectroscopie >]
Biémont, Emile mailto [Université de Liège - ULg > Département de physique > Physique nucléaire, atomique et spectroscopie >]
2010
Astronomy and Astrophysics
EDP Sciences
Yes (verified by ORBi)
International
0004-6361
1432-0746
Les Ulis
France
[en] atomic data ; atomic processes ; Sun: abundances
[en] Aims. We attempt to derive accurate transition probabilities for astrophysically interesting spectral lines of Nb ii and Nb iii and determine the niobium abundance in the Sun and metal-poor stars rich in neutron-capture elements. Methods. We used the time-resolved laser-induced fluorescence technique to measure radiative lifetimes in Nb ii. Branching fractions were measured from spectra recorded using Fourier transform spectroscopy. The radiative lifetimes and the branching fractions were combined yielding transition probabilities. In addition, we calculated lifetimes and transition probablities in Nb ii and Nb iii using a relativistic Hartree-Fock method that includes core polarization. Abundances of the sun and five metal-poor stars were derived using
synthetic spectra calculated with the MOOG code, including hyperfine broadening of the lines.
Results. We present laboratory measurements of 17 radiative lifetimes in Nb ii. By combining these lifetimes with branching fractions for lines depopulating the levels, we derive the transition probabilities of 107 Nb ii lines from 4d35p configuration in the wavelength region 2240−4700 Å. For the first time, we present theoretical transition probabilities of 76 Nb III transitions with wavelengths in the range 1430−3140 Å. The derived solar photospheric niobium abundance log = 1.44 ± 0.06 is in agreement with the meteoritic value. The stellar Nb/Eu abundance ratio determined for five metal-poor stars confirms that the r-process is a dominant production method for the n-capture elements in these stars.
Researchers ; Professionals
http://hdl.handle.net/2268/80611
10.1051/0004-6361/200913574

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