Abundances of Iron and Some Other Elements in the Sun and in Meteorites

Context. To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars, or "benchmark stars", with well-defined parameters to be used as a reference. Aims. We provide detailed documentation of the iron abundance determination of the 34 FGK-type benchmark stars that are selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities, and metallicities. Methods. Up to seven different methods were used to analyze an observed spectral library of high resolutions and high signal-to-noise ratios. The metallicity was determined by assuming a value of effective temperature and surface gravity obtained from fundamental relations; that is, these parameters were known a priori and independently from the spectra. Results. We present a set of metallicity values obtained in a homogeneous way for our sample of benchmark stars. In addition to this value, we provide detailed documentation of the associated uncertainties. Finally, we report a value of the metallicity of the cool giant ψ Phe for the first time.

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“…114: Bridges & Kornblith (1974); Fuhr & Wiese (2006). 129: Garz & Kock (1969);Fuhr et al (1988). 156: May et al (1974.…”

Section: Discussionmentioning

confidence: 99%

GaiaFGK benchmark stars: Metallicity

Jofré

Heiter

Soubiran

et al. 2014

A&A

252

183

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“…Therefore calcium Fraunhofer lines are well-suited for a simultaneous study of weak and strong lines in order to get information about both solar and atomic quantities, that is, about abundance and line-broadening. Following Weidemann (1955), we had performed such a study with sodium (Holweger, 1971, Paper I). The major additional difficulty occurring in the present work arises from the oscillator strenghts of Ca x (Section 3).…”

Section: Introductionmentioning

confidence: 99%

The solar abundance of calcium and collision broadening of Ca i- and Ca ii-Fraunhofer lines by hydrogen

Holweger

1972

Sol Phys

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An abundance analysis of the solar calcium spectrum is carried out using 46 lines with knownfivalues in the visible and near infrared spectral region. Resonance, forbidden and autoionizing lines are included. The solar abundance of calcium resulting from the 25 weaker, nearly dampingindependent lines only is log eca = 6.36 • 0.07, on the scale log e~ = 12. The great variety of transitions involved in the solar calcium spectrum, ranging from 0 eV lines of CaI to 7.5 eV lines of Cau and including autoionizing lines, are in reasonable agreement (Figure 1 b). Therefore notable non-LTE effects on their equivalent widths can be excluded.Together with the sodium abundance log ez~ = 6.30 determined earlier, the solar abundance ratio Ca/Na = 1.15 is obtained with an accuracy of ~ 10%. Comparison with meteorites (carbonaceous chondrites I) shows that solar and meteoritic ratio agree within these limits.The line broadening by collisions with hydrogen atoms is determined empirically from a comparison of weak and strong Fraunhofer lines of CaI and Call, thereby using the solar atmosphere as an absorption tube of comparatively well-known physical state. The damping half-widths 7J~ turn out to be larger than predicted from pure van der Waals interaction, the average enhancement factor being 3.0 for CaI and 1.7for Cau, independent of term properties to a first approximation. Regardless of the reason for this enhancement -inaccurate van der Waals theory or predominance of repulsive interactionthese results can be used in the spectroscopy of other stars.

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“…Sources of f -values: (a) O'Brian et al (1991), (b) May et al (1874), (c) Meylan et al (1993), (e) Blackwell et al (1979), (f) Blackwell et al (1976), (g) Blackwell et al (1982a), (h) Blackwell et al (1982b), (i) Bridges & Kornblith (1974), (j) Garz & Kock (1969), (k) Wolnik et al (1970), (l) Richter & Wulff (1970), (m) Gurtovenko & Kostik (1981), (n) Blackwell et al (1979), (o) Blackwell et al (1980), (p) Bard et al (1991), (q) Bard & Kock (1994). Line synthesis remarks: (a) no blend, no asymmetry, (b) resolved blend(s), (c) continuum adjusted, (d) unresolved blend(s), (e) core asymmetry, (f) blue and red wing deficit, (g) only red wing deficit, (h) core too wide, (i) core too narrow, (j) core too deep, (k) core too shallow, (l) all faint lines included.…”

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Kinetic equilibrium of iron in the atmospheres of cool dwarf stars

Gehren¹,

Korn²,

Shi

2001

A&A

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Abstract. NLTE line formation calculations of Fe i in the solar atmosphere are extended to include weak lines in the visual spectrum of the Sun. Previously established atomic models are used to discriminate between different ways of treating collisional interaction processes. As indicated by the analysis of strong Fe i lines, the influence of deviations from LTE in the solar atmosphere on the Fe abundance is small for all lines. To derive a common solar Fe i abundance from both strong and weak lines fine-tuning of the microturbulence velocity parameter and the van der Waals damping constants is required.

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Abundances of Iron and Some Other Elements in the Sun and in Meteorites

Cited by 58 publications

References 16 publications

GaiaFGK benchmark stars: Metallicity

GaiaFGK benchmark stars: Metallicity

The solar abundance of calcium and collision broadening of Ca i- and Ca ii-Fraunhofer lines by hydrogen

Kinetic equilibrium of iron in the atmospheres of cool dwarf stars

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