Uncertainty of oscillator strengths derived from lifetimes and branching fractions

Sikstrom, C. M; Nilsson, Hampus; Litzén, Ulf; Blom, Anders; Lundberg, Hans

doi:10.1016/s0022-4073(01)00258-8

Cited by 65 publications

(73 citation statements)

References 13 publications

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“…But, as discussed in e.g. Sikström et al (2002), even if a log g f -value has been determined using laboratory measurements, usually through measurements of lifetimes and branching fractions with a claimed high precision there are still uncertainties present.…”

Section: Discussionmentioning

confidence: 99%

Elemental abundance trends in the Galactic thin and thick disks as traced by nearby F and G dwarf stars

Bensby

Feltzing

Lundström

2003

A&A

839

119

1,264

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Abstract. Based on spectra from F and G dwarf stars, we present elemental abundance trends in the Galactic thin and thick disks in the metallicity regime −0.8 [Fe/H] +0.4. Our findings can be summarized as follows. 1) Both the thin and the thick disks show smooth and distinct abundance trends that, at sub-solar metallicities, are clearly separated. 2) For the α-elements the thick disk shows signatures of chemical enrichment from SNe type Ia.3) The age of the thick disk sample is in the mean older than the thin disk sample. 4) Kinematically, there exist thick disk stars with super-solar metallicities. Based on these findings, together with other constraints from the literature, we discuss different formation scenarios for the thick disk. We suggest that the currently most likely formation scenario is a violent merger event or a close encounter with a companion galaxy. Based on kinematics the stellar sample was selected to contain stars with high probabilities of belonging either to the thin or to the thick Galactic disk. The total number of stars are 66 of which 21 belong to the thick disk and 45 to the thin disk. The analysis is based on high-resolution spectra with high signal-to-noise (R ∼ 48 000 and S /N 150, respectively) recorded with the FEROS spectrograph on La Silla, Chile. Abundances have been determined for four α-elements (Mg, Si, Ca, and Ti), for four even-nuclei iron peak elements (Cr, Fe, Ni, and Zn), and for the light elements Na and Al, from equivalent width measurements of ∼30 000 spectral lines. An extensive investigation of the atomic parameters, log g f -values in particular, have been performed in order to achieve abundances that are trustworthy. Noteworthy is that we find for Ti good agreement between the abundances from Ti  and Ti . Our solar Ti abundances are in concordance with the standard meteoritic Ti abundance.

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Section: Discussionmentioning

confidence: 99%

Elemental abundance trends in the Galactic thin and thick disks as traced by nearby F and G dwarf stars

Bensby

Feltzing

Lundström

2003

A&A

839

119

1,264

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“…Astrophysical BFs have similar uncertainties to laboratory measurements including uncertainties in the intensity measurements, intensity calibration and unobservable lines (Sikström et al 2002). Additional uncertainties include corrections for interstellar reddening and blending from other spatial regions along the line of sight.…”

Section: Astrophysical Branching Fractions For a 4 G 11/2mentioning

confidence: 96%

The FERRUM project: transition probabilities for forbidden lines in [Fe II] and experimental metastable lifetimes

Gurell

Hartman

Blackwell-Whitehead

et al. 2009

A&A

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Context. Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [Fe ii] transitions that are observed as strong features in astrophysical spectra.Aims. We measure lifetimes for the 3d 6 ( 3 G)4s a 4 G 11/2 and 3d 6 ( 3 D)4s b 4 D 1/2 metastable levels in Fe ii and experimental transition probabilities for the forbidden transitions 3d 7 a 4 F 7/2,9/2 -3d 6 ( 3 G)4s a 4 G 11/2 . Methods. The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities.

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“…(h) Corliss & Bozman (1962). ( by Sikström et al (2002), which include uncertainties from the line-fitting, intensity calibration of each spectra, intensity cross calibration between separate spectra and the uncertainty in the fit of the decay curve.…”

Section: Transition Probabilitiesmentioning

confidence: 99%

The FERRUM project: laboratory-measured transition probabilities for $\ion{Cr}{\fontsize{9pt}{11pt}\selectfont{II}}$

Gurell¹,

Nilsson

Engström

et al. 2010

A&A

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Aims. We measure transition probabilities for Cr ii transitions from the z 4 H J , z 2 D J , y 4 F J , and y 4 G J levels in the energy range 63 000 to 68 000 cm −1 . Methods. Radiative lifetimes were measured using time-resolved laser-induced fluorescence from a laser-produced plasma. In addition, branching fractions were determined from intensity-calibrated spectra recorded with a UV Fourier transform spectrometer. The branching fractions and radiative lifetimes were combined to yield accurate transition probabilities and oscillator strengths.Results. We present laboratory measured transition probabilities for 145 Cr ii lines and radiative lifetimes for 14 Cr ii levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature.

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Uncertainty of oscillator strengths derived from lifetimes and branching fractions

Cited by 65 publications

References 13 publications

Elemental abundance trends in the Galactic thin and thick disks as traced by nearby F and G dwarf stars

Elemental abundance trends in the Galactic thin and thick disks as traced by nearby F and G dwarf stars

The FERRUM project: transition probabilities for forbidden lines in [Fe II] and experimental metastable lifetimes

The FERRUM project: laboratory-measured transition probabilities for $\ion{Cr}{\fontsize{9pt}{11pt}\selectfont{II}}$

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