The Chemical Composition of the Sun

1. The Chemical Composition of the Sun Martin Asplund, Nicolas Grevesse, A.Jacques Sauval, and Pat Scott citation 1467

2. Outline • The authors • Observation and laboratory datas • Spectrum method • Meteorites method • Helioseismology Method • Solar Neutrinos Method • Summary

3. The Authors Prof. Martin Asplund External Scientific Members in Max Planck Institute for Astrophysics. The Australian National University, Astronomical and Space Sciences. Frontier Technologies for Building and Transforming Australian Industries Asplund got his doctorate in 1997 at Uppsala University with a thesis on variable stars. His research primarily concerns the stars and their composition. H index: 53

4. The Authors Dr. Nicolas Grevesse Centre Spatial de Liège Institut d'Astrophysique et de Géophysique University of Liège, Liège, Belgium H index: 41

5. Solar Abundance Analysis • Observation: • Jungfraujoch (Liege atlas), less affected by telluric absorption owing to the higher observing altitude. • Kitt Peak solar atlas, higher spectral resolving power. • IR disk-center intensity atlases observed from Kitt Peak (ATMOS). • VLT, European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile.

6. Solar Abundance Analysis • Atomic and molecular data • transition probability. • line broadening. • hyperfine and isotopic splitting. • dissociation energies. • gf-values ( laudable work ) (e.g., Kurucz 1992; Johansson et al. 2003; Lawler et al. 2006; Sobeck, Lawler & Sneden 2007). • van der Waals broadening of metal lines (Anstee & O’Mara 1995; Barklem, Piskunov & O’Mara 2000a; Barklem & Aspelund-Johansson 2005).

7. Spectrum Methods • Solar Spectrum • Measure the totle observed line strength. • Directly compare the observed and theoretical spectra through the fitting of the line profiles. • Model of solar atmosphere. • Level populations (LTE & non-LTE).

8. 3D Solar Model

9. 3D Solar Model Code • Trampedach et al. (2009) (extensive used in this paper) • Advantages: • New 3D model satisfies the center-to-limb variation constraint very well. • Even the observed line shifts and asymmetries are very well. • CO5BOLD, Caffau et al. (2008a) (3D) (comparable) • Holweger & Muller (1974) (1D) (comparable)

10. 3D Solar Model

11. Errors • Mean atmospheric stratification. • Taking half of the difference between spatially averaged 3D model and Holweger & Muller (1974) model. • Atmospheric inhomogeneities. • Evaluated as half the difference between the full 3D results and those from spatially averaged 3D. • Departures from LTE • Chosen half of the predicted non-LTE abundance correction as an estimate of the error.

12. Photospheric Abundances • H is defined to be log eH = 12.00 • log ex = log(NX/NH ) + 12 • Calculated from 1 to 90, except 33-35,51-53, 55, 73, 75, 78, 80, 83-89. • Indrict photospheric esimates have been used for noble gases (no photospheric line). • Helium: helioseismology and solar model. • Neon: X-ray and UV spectroscopy of the corona and solar flares, Ne/O ratio. • Argon: solar wind and comparison with other solar system (Jupiter), Ar/O ratio in solar energetic particles. • Krypton: estimated from interpolation of the theoretical s-process production rates. • Xenon: the same with Kr.

13. Meteorites Method • Analysis the meteorites through mass spectroscopy • Group: CI chondrites. • Advantages: modified least over the past 4.56 Gyr. • Disadvantages: volatile elements have been depleted (H, He, C, N, O,Ne). • Calculated from 1 to 92. 5 types: Ivuna, Orgueil, Alais, Tonk and Revelstoke.

14. Meteorites Method Difference between the abundances determined the solar photosphere and the CI carbonaceous chondrites. Li, C, N, and the noble gases fall outside the range of the figure.

15. Abundances vary with Atomic number

16. Helioseismology Method The differences between the helioseismic and predicted sound speeds as a function of depth. The base of the convection zone is at R = 0.71 R ⊙, The better is worse.

17. Helioseismology Method • Aggravated by the further lowering of the solar O and Ne abundances and, to a lesser extent, by the reassessment of C, N, and Fe. • The convection zone is now too shallow: RBCZ ≈ 0.725 R instead of the helioseismic measurement 0.7133 ± 0.0005 R. • He abundance is similarly inconsistent with the value inferred from helioseismology (standard solar model: Ys~0.238, Helioseismology: Ys~0.248).

18. Solutions • The opacities are underestimated (OPAL). • Bahcall et al. (2005) estimated that a 10–20% increase of the OPAL opacities. • The radiative interior contains more metals. • Asplund et al. (2004) first suggested that the diffusion efficiency may be seriously underestimated. • Solar interior side seems to be to invoke some physical process not yet accounted for in standard solar models. • Arnett, Meakin & Young (2005) (internal gravity waves). • Young & Arnett (2005) (multidimensional hydrodynamical simulations of stellar convection zones).

19. Solar Neutrinos Method • Current experiments are not yet sufficiently sensitive to return decisive results in this respect. • The neutrino fluxes cannot be directly associated with abundances of individual elements. • They suspect that the solar neutrinos would favor the new abundances presented herein.

20. Summary • They re-determine the abundances of many chemical elements present in the Sun. • A significantly lower abundances of important abundant elements like Carbon, Nitrogen, Oxygen, Neon, and Iron (by ∼0.2 dex).

21. Thanks !