Volume 573, January 2015
|Number of page(s)||19|
|Published online||11 December 2014|
The elemental composition of the Sun
I. The intermediate mass elements Na to Ca⋆
Department of Physics, Imperial College LondonBlackett
Laboratory, Prince Consort
SW7 2AZ, UK
2 Centre Spatial de Liège, Université de Liège, avenue Pré Aily, 4031 Angleur-Liège, Belgium
3 Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, 17, B5C, 4000 Liège, Belgium
4 Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd., Weston Creek, ACT 2611, Australia
e-mail: martin.asplund; remo.collet]@anu.edu.au
5 Observatoire Royal de Belgique, avenue Circulaire, 3, 1180 Bruxelles, Belgium
6 Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
7 National Astronomical Observatory of Japan, 2-21-1 Osawa, 181-8588 Tokyo, Japan
8 Stellar Astrophysics Centre, Department of Physics ad Astronomy, Aarhus University, 8000 Aarhus C, Denmark
9 JILA, University of Colorado and National Institute of Standards and Technology, 440 UCB, Boulder, CO 80309, USA
Received: 1 May 2014
Accepted: 1 September 2014
The chemical composition of the Sun is an essential piece of reference data for astronomy, cosmology, astroparticle, space and geo-physics: elemental abundances of essentially all astronomical objects are referenced to the solar composition, and basically every process involving the Sun depends on its composition. This article, dealing with the intermediate-mass elements Na to Ca, is the first in a series describing the comprehensive re-determination of the solar composition. In this series we severely scrutinise all ingredients of the analysis across all elements, to obtain the most accurate, homogeneous and reliable results possible. We employ a highly realistic 3D hydrodynamic model of the solar photosphere, which has successfully passed an arsenal of observational diagnostics. For comparison, and to quantify remaining systematic errors, we repeat the analysis using three different 1D hydrostatic model atmospheres (marcs, miss and Holweger & Müller 1974, Sol. Phys., 39, 19) and a horizontally and temporally-averaged version of the 3D model (⟨ 3D ⟩). We account for departures from local thermodynamic equilibrium (LTE) wherever possible. We have scoured the literature for the best possible input data, carefully assessing transition probabilities, hyperfine splitting, partition functions and other data for inclusion in the analysis. We have put the lines we use through a very stringent quality check in terms of their observed profiles and atomic data, and discarded all that we suspect to be blended. Our final recommended 3D+NLTE abundances are: log ϵNa = 6.21 ± 0.04, log ϵMg = 7.59 ± 0.04, log ϵAl = 6.43 ± 0.04, log ϵSi = 7.51 ± 0.03, log ϵP = 5.41 ± 0.03, log ϵS = 7.13 ± 0.03, log ϵK = 5.04 ± 0.05 and log ϵCa = 6.32 ± 0.03. The uncertainties include both statistical and systematic errors. Our results are systematically smaller than most previous ones with the 1D semi-empirical Holweger & Müller model, whereas the ⟨ 3D ⟩ model returns abundances very similar to the full 3D calculations. This analysis provides a complete description and a slight update of the results presented in Asplund et al. (2009, ARA&A, 47, 481) for Na to Ca, and includes full details of all lines and input data used.
Key words: Sun: abundances / Sun: photosphere / Sun: granulation / line: formation / line: profiles / convection
Tables 1–4 and Appendix A are available in electronic form at http://www.aanda.org
© ESO, 2014
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