Absolute oscillator strengths for 108 lines of SI I between 163 and 410 nanometers

Smith, Peter L.; Huber, M. C. E.; Tozzi, G. P.; Griesinger, H. E.; Cardon, Bartley L.; Lombardi, Gabriel G.

doi:10.1086/165752

Cited by 31 publications

(16 citation statements)

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“…However the oscillator strength for 3p − 6s is much smaller than it is for 3p − 5s or 3p − 4s. For the 3p − 3d( 3 D 1 ) transition, our calculated value is in good agreement with the experimental data of Smith et al (1987), and with various theoretical data. For the 3p − 3d( 3 P 1 ) transition, our value is higher than the experimental and theoretical data, by a factor of 2 in some cases.…”

Section: Cross Sectionssupporting

confidence: 89%

“…If we limit our consideration to the three transitions with the largest oscillator strengths: 3p − 3d( 3 D 1 ), 3p − 4s( 3 P 1 ), and 3p − 4d( 3 D 1 ), and if we compare these oscillator strengths with those of Smith et al (1987), which are the most extensive experimental data available on Si i, we find that our results have an accuracy in the range 7% to 23%. We therefore estimate our high energy cross sections to have an accuracy somewhere in this range.…”

Section: Cross Sectionsmentioning

confidence: 88%

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Electron impact excitation of SiI

Ganas

1999

Astron. Astrophys. Suppl. Ser.

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Abstract. An analytic atomic independent-particle-model is used to generate wave functions for the valence and excited states of the neutral silicon atom. These wave functions are used to calculate generalized oscillator strengths, and from these quantities the cross sections are obtained in the Born approximation. Various excitations from the ground state, 3p2 ( 3 P 0 ), are considered, and results are presented for electron impact energies up to 5 keV.

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Section: Cross Sectionssupporting

confidence: 89%

Section: Cross Sectionsmentioning

confidence: 88%

Electron impact excitation of SiI

Ganas

1999

Astron. Astrophys. Suppl. Ser.

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“…Adopting a slightly larger gf value for λ 4102 Å, e.g. from Smith et al (1987) rather than Garz (1973), would improve the agreement with observation; on the other hand, we have neglected collisional coupling within the 3 P e term, which might be important if we have underestimated the densities in the line-forming region. At this point, therefore, we cannot use the ratio of the EEWs to constrain the current model further, but it is not inconsistent.…”

Section: Escape Probability Modelmentioning

confidence: 87%

Orbitally modulated photoexcited Si i emission in the eclipsing composite-spectrum binary ζ Aurigae

Harper

Griffin

Bennett

et al. 2015

Mon. Not. R. Astron. Soc.

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We examine the little-known phenomenon of orbitally modulated Si I emission at λ 3905.523 Å and λ 4102.936 Å in composite-spectrum binaries, with specific reference to ζ Aurigae (K4 Ib + B5 V). The emission is detected in the isolated spectrum of the Btype dwarf secondary, and while λ 4102 Å is heavily blended with Hδ, λ 3905 Å falls in the B-star's featureless continuum. The narrowness of the emission (v turb 6 km s −1 ) demonstrates that it originates in the upper photosphere or deep chromosphere of the K star primary. We propose that photoexcitation by the hot star's UV continuum, followed by recombination and cascades, leads to resonant scattering and subsequent pumping of lower opacity transitions in the singlet and triplet systems of Si I. This process channels the UV continuum into select narrow emission lines. We have also identified weaker photoexcited emission of Fe II at λ 3938.289 Å. The strengths, positions, and widths of the λ 3905 Å emission line vary with orbital phase owing to changes in the dilution of the irradiating flux and in the geometrical aspect of the irradiated hemisphere. Utilizing the inherent spatial resolution provided by the illuminated patch, and assuming that the K star is spherical with isotropic emission, yields vsin i ∼ 5.7 km s −1 . Evidence of tidal distortion was deduced from the timing of the rapidly rising phase of the emission just after periastron. Increasing the diagnostic potential requires radiative transfer modelling of the formation and centre-to-limb variation of the emission.

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“…Since the lifetime experiments of Savage & Lawrence (1966) and Marek & Richter (1973) there has been an ongoing discussion of the measurements regarding the lifetime of the Si i 4s 3 P o 2 level. While all other level lifetimes led to consistent results, this showed controversial values depending on the experimental method used (Bashkin et al 1980;Becker et al 1980a,b;Smith et al 1987). The lifetime measurements of the 4s 3 P o 2 level were carried out with three methods: phase shift, beam foil, and laser fluorescence, of which the last, used by Becker et al (1980a), should be the most reliable.…”

Section: Line Synthesis and The Solar Si Abundancementioning

confidence: 99%

Statistical equilibrium of silicon in the solar atmosphere

Shi

Gehren

Butler

et al. 2008

A&A

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Aims. The statistical equilibrium of neutral and ionised silicon in the solar photosphere is investigated. Line formation is discussed and the solar silicon abundance determined. Methods. High-resolution solar spectra were used to determine solar log g f ε Si values by comparison with Si line synthesis based on LTE and NLTE level populations. The results will be used in a forthcoming paper for differential abundance analyses of metalpoor stars. A detailed analysis of silicon line spectra leads to setting up realistic model atoms, which are exposed to interactions in plane-parallel solar atmospheric models. The resulting departure coefficients are entered into a line-by-line analysis of the visible and near-infrared solar silicon spectrum.Results. The statistical equilibrium of Si i turns out to depend marginally on bound-free interaction processes, both radiative and collisional. Bound-bound interaction processes do not play a significant role either, except for hydrogen collisions, which have to be chosen adequately for fitting the cores of the near-infrared lines. Except for some near-infrared lines, the NLTE influence on the abundances is weak. Conclusions. Taking the deviations from LTE in silicon into account, it is possible to calculate the ionisation equilibrium from neutral and ionised lines. The solar abundance based on the experimental f -values of Garz corrected for the Becker et al.'s measurement is 7.52 ± 0.05. Combined with an extended line sample with selected NIST f -values, the solar abundance is 7.52 ± 0.06, with a nearly perfect ionisation equilibrium of Δ log ε (Si ii/Si i) = −0.01.

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Absolute oscillator strengths for 108 lines of SI I between 163 and 410 nanometers

Cited by 31 publications

References 0 publications

Electron impact excitation of SiI

Electron impact excitation of SiI

Orbitally modulated photoexcited Si i emission in the eclipsing composite-spectrum binary ζ Aurigae

Statistical equilibrium of silicon in the solar atmosphere

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