Database for inelastic collisions of sodium atoms with electrons, protons, and multiply charged ions

Igenbergs, Katharina; Schweinzer, J.; Bray, Igor; Bridi, D.; Aumayr, F.

doi:10.1016/j.adt.2008.06.001

Cited by 23 publications

(15 citation statements)

References 65 publications

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“…In this case, we used electron collision crosssections from Igenbergs et al (2008) for transitions between the lowest eight energy levels of the sodium atom, for a wide range of impacting electron energies. Electron ionisation crosssections were also taken from Igenbergs et al (2008). For the rest of the allowed transitions we used the relation of van Regemorter (1962), while for the forbidden transitions the formula of Allen (1973) was utilised.…”

Section: Model Atom Of Sodiummentioning

confidence: 99%

Abundances of lithium, oxygen, and sodium in the turn-off stars of Galactic globular cluster 47 Tucanae

Dobrovolskas

Kučinskas

Bonifacio

et al. 2014

A&A

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Context. The cluster 47 Tuc is among the most metal-rich Galactic globular clusters and its metallicity is similar to that of metal-poor disc stars and open clusters. Like other globular clusters, it displays variations in the abundances of elements lighter than Si, which is generally interpreted as evidence of the presence of multiple stellar populations. Aims. We aim to determine abundances of Li, O, and Na in a sample of of 110 turn-off (TO) stars, in order to study the evolution of light elements in this cluster and to put our results in perspective with observations of other globular and open clusters, as well as with field stars. Methods. We use medium resolution spectra obtained with the GIRAFFE spectrograph at the ESO 8.2 m Kueyen VLT telescope and use state of the art 1D model atmospheres and NLTE line transfer to determine the abundances. We also employ CO 5 BOLD hydrodynamical simulations to assess the impact of stellar granulation on the line formation and inferred abundances. Results. Our results confirm the existence of Na-O abundance anti-correlation and hint towards a possible Li-O anti-correlation in the TO stars of 47 Tuc. At the same time, we find no convincing evidence supporting the existence of Li-Na correlation. The obtained 3D NLTE mean lithium abundance in a sample of 94 TO stars where Li lines were detected reliably, A(Li) 3D NLTE = 1.78 ± 0.18 dex, appears to be significantly lower than what is observed in other globular clusters. At the same time, star-to-star spread in Li abundance is also larger than seen in other clusters. The highest Li abundance observed in 47 Tuc is about 0.1 dex lower than the lowest Li abundance observed among the un-depleted stars of the metal-poor open cluster NGC 2243. Conclusions. The correlations/anti-correlations among light element abundances confirm that chemical enrichment history of 47 Tuc was similar to that of other globular clusters, despite the higher metallicity of 47 Tuc. The lithium abundances in 47 Tuc, when put into context with observations in other clusters and field stars, suggest that stars that are more metal-rich than [Fe/H] ∼ −1.0 experience significant lithium depletion during their lifetime on the main sequence, while the more metal-poor stars do not. Rather strikingly, our results suggest that initial lithium abundance with which the star was created may only depend on its age (the younger the star, the higher its Li content) and not on its metallicity.

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Section: Model Atom Of Sodiummentioning

confidence: 99%

Abundances of lithium, oxygen, and sodium in the turn-off stars of Galactic globular cluster 47 Tucanae

Dobrovolskas

Kučinskas

Bonifacio

et al. 2014

A&A

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“…The atomic transition and electron loss processes due to electron (e), proton (p) and impurity (I) collisions are described by the reduced rate coefficient matrixã ij [4,15,16,17]. Taking the effect of the impurities into account through one representative impurity characterized by charge q(x) and producing an effective ion charge Z ef f (x), the matrix is written asã ij = a e ij + (1 − qf )a p ij + f a I ij , where f = (Z ef f − 1)/(q(q − 1)).…”

Section: Renate Alkali Bes Measurement Simulationmentioning

confidence: 99%

“…The collisional j → i de-excitation rate coefficients are derived from the corresponding i → j excitation rate coefficients using the principle of detailed balance, while impurity collision rate coefficients are calculated from the proton collisional cross sections using the scaling relations given in [4,15]. The proton impact target electron loss processes are considered instead of treating the ionization and charge exchange channels separately, which is the main difference of the atomic physics kernel from the Absolut [6] inverse problem solver regarding the atomic physics.…”

Section: Renate Alkali Bes Measurement Simulationmentioning

confidence: 99%

“…The spontaneous atomic transition probabilities are taken from the NIST atomic spectra database [18], and the cross section data found in [15,16,17] for lithium and [4] for sodium are used. The collisional j → i de-excitation rate coefficients are derived from the corresponding i → j excitation rate coefficients using the principle of detailed balance, while impurity collision rate coefficients are calculated from the proton collisional cross sections using the scaling relations given in [4,15].…”

Section: Renate Alkali Bes Measurement Simulationmentioning

confidence: 99%

“…The emission reconstruction correction method is discussed in Sec. 4, and demonstrated through realistic simulated measurements in Sec. 5.…”

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Database for inelastic collisions of sodium atoms with electrons, protons, and multiply charged ions

Cited by 23 publications

References 65 publications

Abundances of lithium, oxygen, and sodium in the turn-off stars of Galactic globular cluster 47 Tucanae

Abundances of lithium, oxygen, and sodium in the turn-off stars of Galactic globular cluster 47 Tucanae

Deconvolution-based correction of alkali beam emission spectroscopy density profile measurements

PAMOP2: State-of-the-Art Computations for Atomic, Molecular and Optical Processes

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