Transition Probabilities Of Astrophysical Interest In The Niobium Ions Nb+ And Nb2+

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dc.contributor.utaustinauthorSneden, Christopheren_US
dc.creatorNilsson, H.en_US
dc.creatorHartman, H.en_US
dc.creatorEngstrom, L.en_US
dc.creatorLundberg, H.en_US
dc.creatorSneden, Christopheren_US
dc.creatorFivet, V.en_US
dc.creatorPalmeri, P.en_US
dc.creatorQuinet, P.en_US
dc.creatorBiemont, E.en_US
dc.date.accessioned2016-04-22T19:47:11Z
dc.date.available2016-04-22T19:47:11Z
dc.date.issued2010en
dc.description.abstractAims. 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 4d(3)5p configuration in the wavelength region 2240-4700 angstrom. For the first time, we present theoretical transition probabilities of 76 Nb III transitions with wavelengths in the range 1430-3140 angstrom. The derived solar photospheric niobium abundance log epsilon(circle dot) = 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.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipIntegrated Initiative of Infrastructure RII3-CT-2003-506350en_US
dc.description.sponsorshipSwedish Research Councilen_US
dc.description.sponsorshipKnut and Alice Wallenberg Foundationen_US
dc.description.sponsorshipBelgian FRS-FNRSen_US
dc.description.sponsorshipFRIAen_US
dc.description.sponsorshipUS National Science Foundation AST-0607708, AST-0908978en_US
dc.identifierdoi:10.15781/T2WN5K
dc.identifier.citationNilsson, Hampus, Henrik Hartman, Lars Engström, Hans Lundberg, Christopher Sneden, Vanessa Fivet, Patrick Palmeri, Pascal Quinet, and É. Biémont. >Transition Probabilities Of Astrophysical Interest In The Niobium Ions Nb+ And Nb2+> Astronomy & Astrophysics, Vol. 511 (Feb.\Mar., 2010): A16.en_US
dc.identifier.doi10.1051/0004-6361/200913574en_US
dc.identifier.issn0004-6361en_US
dc.identifier.urihttp://hdl.handle.net/2152/34479
dc.language.isoEnglishen_US
dc.relation.ispartofserialAstronomy & Astrophysicsen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectatomic dataen_US
dc.subjectatomic processesen_US
dc.subjectsun: abundancesen_US
dc.subjectstars: abundancesen_US
dc.subjectmetal-poor starsen_US
dc.subjectr-process-richen_US
dc.subjectoscillator-strengthsen_US
dc.subjectradiativeen_US
dc.subjectlifetimesen_US
dc.subjecttheoretical lifetimesen_US
dc.subjectchemical-compositionen_US
dc.subjectbranchingen_US
dc.subjectfractionsen_US
dc.subjectlaser spectroscopyen_US
dc.subjectsolar abundanceen_US
dc.subjects-processen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleTransition Probabilities Of Astrophysical Interest In The Niobium Ions Nb+ And Nb2+en_US
dc.typeArticleen_US

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