Electron-impact excitation and ionization of atomic calcium at intermediate energies

Zatsarinny, Oleg; Parker, H.; Bartschat, Klaus

doi:10.1103/physreva.99.012706

Cited by 15 publications

(16 citation statements)

References 32 publications

(65 reference statements)

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“…Our new Ca model atom consists of 141 Ca i levels, 46 Ca ii levels, and the Ca iii ground state, which are coupled radiatively by 2271 bound-bound and 135 bound-free transitions. We employ data for inelastic collisions with electrons from Zatsarinny et al (2019b) for Ca i and from Meléndez et al (2007) for Ca ii; while for inelastic collisions with neutral hydrogen we draw on data from Barklem (2016b) and Belyaev et al (2018) for Ca i and Ca ii respectively. Osorio et al (2020) reported a non-negligible influence of non-LTE effects on Mg i influencing the statistical equilibrium of Ca in the Sun.…”

Section: Intermediate Mass Elements: Sodium To Calciummentioning

confidence: 99%

The chemical make-up of the Sun: A 2020 vision

Asplund,

Amarsi,

Grevesse

2021

Preprint

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Context. The chemical composition of the Sun is a fundamental yardstick in astronomy, relative to which essentially all cosmic objects are referenced. As such, having an accurate knowledge of the solar elemental abundances is crucial for an extremely broad range of topics. Aims. We reassess the solar abundances of all 83 long-lived elements, using highly realistic solar modelling and state-of-the-art spectroscopic analysis techniques coupled with the best available atomic data and observations. Methods. The basis for our solar spectroscopic analysis is a 3D radiative-hydrodynamical model of the solar surface convection and atmosphere, which reproduces the full arsenal of key observational diagnostics. New complete and comprehensive 3-dimensional (3D) spectral line formation calculations taking into account of departures from local thermodynamic equilibrium (non-LTE) are presented for Na, Mg, K, Ca, and Fe using comprehensive model atoms with reliable radiative and collisional data. Our newly derived abundances for C, N, and O are based on a 3D non-LTE analysis of permitted and forbidden atomic lines as well as 3D LTE calculations for in total 879 molecular transitions of CH, C 2 , CO, NH, CN, and OH. Previous 3D-based calculations for another 50 elements are re-evaluated based on updated atomic data, stringent selection of lines, improved consideration of blends, and new non-LTE calculations available in the literature. For elements where spectroscopic determinations of the quiet Sun are not possible the recommended solar abundances are revisited based on complementary methods, including helioseismology (He), solar wind data from the Genesis sample return mission (noble gases), sunspot observations (four elements) and measurements of the most primitive meteorites (15 elements). Results. Our new improved analysis confirms the relatively low solar abundances of C, N, and O obtained in our previous 3Dbased studies: log C = 8.46 ± 0.04, log N = 7.83 ± 0.07, and log O = 8.69 ± 0.04. Excellent agreement between all available atomic and molecular indicators is achieved for C and O, but for N the atomic lines imply a lower abundance than for the molecular transitions for unknown reasons. The revised solar abundances for the other elements also typically agree well with our previously recommended values with just Li, F, Ne, Mg, Cl, Kr, Rb, Rh, Ba, W, Ir, and Pb differing by more than 0.05 dex. The here advocated present-day photospheric metal mass fraction is only slightly higher than our previous value, mainly due to the revised Ne abundance from Genesis solar wind measurements: X surface = 0.7438 ± 0.0054, Y surface = 0.2423 ± 0.0054, Z surface = 0.0139 ± 0.0006, and Z surface /X surface = 0.0187 ± 0.0009. Overall the solar abundances agree well with those of CI chondritic meteorites but we identify a correlation with condensation temperature such that moderately volatile elements are enhanced by ≈ 0.04 dex in the CI chondrites and refractory elements possibly depleted by ≈ 0.02 dex, conflicting with conventional wisdom...

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Section: Intermediate Mass Elements: Sodium To Calciummentioning

confidence: 99%

The chemical make-up of the Sun: A 2020 vision

Asplund,

Amarsi,

Grevesse

2021

Preprint

View full text Add to dashboard Cite

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“…Continuum data were taken from the TOPBASE database (Cunto & Mendoza 1992). Hydrogen collisions (Belyaev et al 2012; Barklem 2016Barklem , 2017a and electron collisions (Meléndez et al 2007;Zatsarinny et al 2019;Barklem et al 2017) were included in the NLTE calculations, when no data were available, approximation formulas were used. Our Mg model atoms have 96 levels of Mg i, 29 of Mg ii and the ground level of Mg iii.…”

Section: Mg and Camentioning

confidence: 99%

“…In this work, hydrogen collisional excitation for the high-lying levels of Ca i were ignored, while we used the formula from Kaulakys (1986). For electron collisional ionisation Zhou et al used the formula from Seaton (1962), while we adopted the formula from Vrinceanu (2005); fi-Table 6: log(gf) values adopted for the Ca i lines visible in the H-band in Zhou et al (2019) nally, electron collisional data involving the levels producing the Ca i lines visible in the H-band are from Seaton (1962), while we used an extension of the data presented in Zatsarinny et al (2019).…”

Section: Other Nlte Work In the Apogee Windowmentioning

confidence: 99%

NLTE for APOGEE: simultaneous multi-element NLTE radiative transfer

Osorio

Prieto

Hubený

et al. 2020

A&A

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Context. Relaxing the assumption of Local Thermodynamic Equilibrium (LTE) in modelling stellar spectra is a necessary step to determine chemical abundances better than about 10 % in late-type stars. Aims. In this paper we describe our efforts gearing up to perform multi-element (Na, Mg, K, and Ca) Non-LTE (NLTE) calculations that can be applied to the APOGEE survey. Methods. The new version of TLUSTY allows for the calculation of restricted NLTE in cool stars using pre-calculated opacity tables. We demonstrate that TLUSTY gives consistent results with MULTI, a well-tested code for NLTE in cool stars. We use TLUSTY to perform LTE and a series of NLTE calculations using all combinations of 1, 2, 3 and the 4 elements mentioned above simultaneously in NLTE. Results. In this work we take into account how departures from LTE in one element can affect others through changes in the opacities of Na, Mg, K, and Ca. We find that atomic Mg, which provides strong UV opacity, and exhibits significant departures from LTE in the low-energy states, can impact the NLTE populations of Ca, leading to abundance corrections as large as 0.07 dex. The differences in the derived abundances between the single-element and the multi-element cases can exceed those between the single-element NLTE determinations and an LTE analysis, warning that this is not always a second-order effect. By means of detailed tests for three stars with reliable atmospheric parameters (Arcturus, Procyon and the Sun) we conclude that our NLTE calculations provide abundance corrections that can amount in the optical up to 0.1, 0.2 and 0.7 dex for Ca, Na and K, but LTE is a good approximation for Mg. In the H-band, NLTE corrections are much smaller, and always under to 0.1 dex. The derived NLTE abundances in the optical and in the IR are consistent. For all four elements, in all three stars, NLTE line profiles fit better the observations than the LTE counterparts. Conclusions. The atomic elements in ionisation stages where over-ionisation is an important NLTE mechanism are likely affected by departures from LTE in Mg . Special care must be taken with the collisions adopted for high-lying levels when calculating NLTE profiles of lines in the H-band. The derived NLTE corrections in the optical and in the H-band differ, but the derived NLTE abundances are consistent between the two spectral regions.

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“…Fe ii; while for inelastic collisions with neutral hydrogen, we drew on data fromBarklem (2018) andYakovleva et al (2019) for Fe i and Fe ii, respectively. Photoionisation cross-sections for Fe i were sourced fromZatsarinny et al (2019a). Recently, new accurate experimental transition probabilities for additional excellent solar Fe i lines have been published(Den Hartog et al 2014;Belmonte et al 2017), which we employed together with previous lines used byScott et al (2015a) with the transition probabilities recommended by the Oxford (e.g.,Blackwell et al 1995), Hannover (e.g.,Holweger et al 1991), and Wisconsin (e.g., O'…”

mentioning

confidence: 99%

The chemical make-up of the Sun: A 2020 vision

Asplund

Amarsi

Grevesse

2021

A&A

335

270

View full text Add to dashboard Cite

Context. The chemical composition of the Sun is a fundamental yardstick in astronomy, relative to which essentially all cosmic objects are referenced. As such, having accurate knowledge of the solar elemental abundances is crucial for an extremely broad range of topics. Aims. We reassess the solar abundances of all 83 long-lived elements, using highly realistic solar modelling and state-of-the-art spectroscopic analysis techniques coupled with the best available atomic data and observations. Methods. The basis for our solar spectroscopic analysis is a three-dimensional (3D) radiative-hydrodynamical model of the solar surface convection and atmosphere, which reproduces the full arsenal of key observational diagnostics. New complete and comprehensive 3D spectral line formation calculations taking into account of departures from local thermodynamic equilibrium (non-LTE) are presented for Na, Mg, K, Ca, and Fe using comprehensive model atoms with reliable radiative and collisional data. Our newly derived abundances for C, N, and O are based on a 3D non-LTE analysis of permitted and forbidden atomic lines as well as 3D LTE calculations for a total of 879 molecular transitions of CH, C2, CO, NH, CN, and OH. Previous 3D-based calculations for another 50 elements are re-evaluated based on updated atomic data, a stringent selection of lines, improved consideration of blends, and new non-LTE calculations available in the literature. For elements where spectroscopic determinations of the quiet Sun are not possible, the recommended solar abundances are revisited based on complementary methods, including helioseismology (He), solar wind data from the Genesis sample return mission (noble gases), sunspot observations (four elements), and measurements of the most primitive meteorites (15 elements). Results. Our new improved analysis confirms the relatively low solar abundances of C, N, and O obtained in our previous 3D-based studies: log ϵC = 8.46 ± 0.04, log ϵN = 7.83 ± 0.07, and log ϵO = 8.69 ± 0.04. Excellent agreement between all available atomic and molecular indicators is achieved for C and O, but for N the atomic lines imply a lower abundance than for the molecular transitions for unknown reasons. The revised solar abundances for the other elements also typically agree well with our previously recommended values, with only Li, F, Ne, Mg, Cl, Kr, Rb, Rh, Ba, W, Ir, and Pb differing by more than 0.05 dex. The here-advocated present-day photospheric metal mass fraction is only slightly higher than our previous value, mainly due to the revised Ne abundance from Genesis solar wind measurements: Xsurface = 0.7438 ± 0.0054, Ysurface = 0.2423 ± 0.0054, Zsurface = 0.0139 ± 0.0006, and Zsurface/Xsurface = 0.0187 ± 0.0009. Overall, the solar abundances agree well with those of CI chondritic meteorites, but we identify a correlation with condensation temperature such that moderately volatile elements are enhanced by ≈0.04 dex in the CI chondrites and refractory elements possibly depleted by ≈0.02 dex, conflicting with conventional wisdom of the past half-century. Instead, the solar chemical composition more closely resembles that of the fine-grained matrix of CM chondrites with the expected exception of the highly volatile elements. Conclusions. Updated present-day solar photospheric and proto-solar abundances are presented for 83 elements, including for all long-lived isotopes. The so-called solar modelling problem – a persistent discrepancy between helioseismology and solar interior models constructed with a low solar metallicity similar to that advocated here – remains intact with our revised solar abundances, suggesting shortcomings with the computed opacities and/or treatment of mixing below the convection zone in existing standard solar models. The uncovered trend between the solar and CI chondritic abundances with condensation temperature is not yet understood but is likely imprinted by planet formation, especially since a similar trend of opposite sign is observed between the Sun and solar twins.

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Electron-impact excitation and ionization of atomic calcium at intermediate energies

Cited by 15 publications

References 32 publications

The chemical make-up of the Sun: A 2020 vision

The chemical make-up of the Sun: A 2020 vision

NLTE for APOGEE: simultaneous multi-element NLTE radiative transfer

The chemical make-up of the Sun: A 2020 vision

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