A non-LTE study of neutral and singly-ionized iron line spectra in 1D models of the Sun and selected late-type stars

Mashonkina, L.; Gehren, T.; Shi, Jianrong; Korn, A. J.; Grupp, F.

doi:10.1051/0004-6361/201015336

Cited by 233 publications

(296 citation statements)

References 76 publications

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“…For HD 122563 we adopted T eff = 4600 K from Mashonkina et al (2011), and it is consistent with the recent value based on the interferometric observations of Creevey et al (2012 Notes. References: (1) Mashonkina et al (2003); (2) Mashonkina et al (2011); (3) Sitnova et al (2015) recommended by Sitnova et al (2015) based on the data of Alonso et al (1996), González Hernández & Bonifacio (2009), Casagrande et al (2010, and Casagrande et al (2011).…”

Section: Stellar Sample Observations and Stellar Parameterssupporting

confidence: 74%

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Carbon abundances of reference late-type stars from 1D analysis of atomic C i and molecular CH lines

Alexeeva

Mashonkina

2015

Mon. Not. R. Astron. Soc.

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A comprehensive model atom was constructed for C I using the most up-to-date atomic data. We evaluated non-local thermodynamical equilibrium (NLTE) line formation for neutral carbon in classical 1D models representing atmospheres of late-type stars, where carbon abundance varies from solar value down to [C/H] = −3. NLTE leads to stronger C I lines compared with their LTE strength and negative NLTE abundance corrections, ∆ NLTE . The deviations from LTE are large for the strong lines in the infrared (IR), with ∆ NLTE = −0.10 dex to −0.45 dex depending on stellar parameters, and they are minor for the weak lines in the visible spectral range, with |∆ NLTE | 0.03 dex. The NLTE abundance corrections were found to be dependent of the carbon abundance in the model. As the first application of the treated model atom, carbon NLTE abundances were determined for the Sun and eight late-type stars with well-determined stellar parameters that cover the −2.56 [Fe/H] −1.02 metallicity range. Consistent abundances from the visible and IR lines were found for the Sun and the most metal-rich star of our sample, when applying a scaling factor of S H = 0.3 to the Drawinian rates of C+H collisions. Carbon abundances were also derived from the molecular CH lines and, for each star, they agree with that from the atomic C I lines. We present the NLTE abundance corrections for lines of C I in the grid of model atmospheres applicable to the carbon-enhanced (CEMP) stars.

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Section: Stellar Sample Observations and Stellar Parameterssupporting

confidence: 74%

“…The opacity package was improved as described in Mashonkina et al (2011). The departure coefficients, bi = nNLTE / nLTE, were then used to com- pute synthetic line profiles via the SIU (Spectrum Investigation Utility) code (Reetz 1991).…”

Section: Methods Of Calculationsmentioning

confidence: 99%

Carbon abundances of reference late-type stars from 1D analysis of atomic C i and molecular CH lines

Alexeeva

Mashonkina

2015

Mon. Not. R. Astron. Soc.

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“…The update was presented by Mashonkina et al (2011). The obtained departure coefficients were then used by the codes SIU (Reetz 1991) and SYNTHV-NLTE to calculate the synthetic line profiles.…”

Section: Nlte Methodsmentioning

confidence: 99%

SYSTEMATIC NON-LTE STUDY OF THE −2.6 ≤ [Fe/H] ≤ 0.2 F AND G DWARFS IN THE SOLAR NEIGHBORHOOD. II. ABUNDANCE PATTERNS FROM Li TO Eu*

Zhao

Mashonkina

Yan

et al. 2016

ApJ

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147

158

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For the first time, we present an extensive study of stars with individual non-LTE (NLTE) abundances for 17 chemical elements from Li to Eu in a sample of stars uniformly distributed over the −2.62 [Fe/H] +0.24 metallicity range that is suitable for the Galactic chemical evolution research. The star sample has been kinematically selected to trace the Galactic thin and thick disks and halo. We find new results and improve earlier ones as follows: (i) the element-to-iron ratios for Mg, Si, Ca, and Ti form a metal-poor (MP) plateau at a similar height of 0.3 dex, and the knee occurs at common

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“…At sub-solar metallicities and gravities, however, neutral species become underpopulated relative to the LTE case, owing to the ultraviolet over-ionization and the lower rate of collisions, resulting in the positive corrections that need to be added to the LTE abundances (Rentzsch-Holm 1996;Bergemann 2011;Mashonkina et al 2011). Observationally, this is manifested in the case of the supergiants, where Fe I lines require smaller values of V tur and log g to bring their abundances into agreement with the more well-behaved Fe II lines (which is the dominant ionization state in F-G stars), as shown for example in Kovtyukh & Andrievsky (1999) for the classical Cepheid δ Cep and in Takeda et al (2007) for some post-AGB stars.…”

Section: Photospheric Parametersmentioning

confidence: 99%

Time-resolved spectroscopy of BD+46°442: Gas streams and jet creation in a newly discovered evolved binary with a disk

Gorlova

Winckel

Gielen

et al. 2012

A&A

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Context. Previous studies have shown that many post-asymptotic giant branch (AGB) stars with dusty disks are associated with single-lined binary stars. The inferred orbital separations are too small to accommodate a fully grown AGB star, hence these systems represent a new evolutionary channel that bypasses a full AGB evolution. Aims. We wish to verify the binarity hypothesis for a larger sample establish the nature of the companions, and probe the disk structure and eventually the disk formation mechanisms in binary stars. To achieve these aims, we started a high-resolution spectral monitoring of ∼40 field giants whose binarity had been suspected based on either a light curve, an infrared excess, or a peculiar chemical composition. Methods. Starting from the spring of 2009, we monitored the programme stars with the fibre echelle spectrometer HERMES. We measure their radial velocities (RVs) with a precision of ∼0.2 km s −1 , perform detailed photospheric abundance analyses, and analyse the time-resolved high-resolution spectra to search for line-profile variability.Results. Here we report on the discovery of periodic RV variations in BD+46 • 442, a high Galactic latitude F giant with a disk. We infer that the variations are caused by the motion around a faint companion, and deduce the orbital parameters P orb = 140.77 ± 0.02 d , e = 0.083± 0.002, and a sin i = 0.31 AU. We find that it is a moderately metal-poor star ([M/H] = −0.7) without a strong depletion pattern in its photospheric abundances. Interestingly, many lines indeed show periodic changes with the orbital phase: Hα switches between a double-peak emission line and a P Cyg-like profile, while strong metal lines appear to be split at the maximum redshift. Similar effects are likely visible in the spectra of other post-AGB binaries, but their regularity is not always apparent owing to sporadic observations. We propose that these features result from an ongoing mass transfer from the evolved giant to the companion. In particular, the blueshifted absorption in Hα, which occurs only at superior conjunction, may result from a jet originating in the accretion disk around the companion and that is seen in absorption towards the luminous primary.

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A non-LTE study of neutral and singly-ionized iron line spectra in 1D models of the Sun and selected late-type stars

Cited by 233 publications

References 76 publications

Carbon abundances of reference late-type stars from 1D analysis of atomic C i and molecular CH lines

Carbon abundances of reference late-type stars from 1D analysis of atomic C i and molecular CH lines

SYSTEMATIC NON-LTE STUDY OF THE −2.6 ≤ [Fe/H] ≤ 0.2 F AND G DWARFS IN THE SOLAR NEIGHBORHOOD. II. ABUNDANCE PATTERNS FROM Li TO Eu*

Time-resolved spectroscopy of BD+46°442: Gas streams and jet creation in a newly discovered evolved binary with a disk

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