Determining Solar Abundances Using Helioseismology

Antia, H. M.; Basu, Sarbani

doi:10.1086/503707

Cited by 96 publications

(76 citation statements)

References 39 publications

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“…However, in this work only low degree modes are used, while the higher degree modes also provide independent constraints. Also our mode,l which is the closest to the observations, has a surface metallicity content Z smaller than the value determined by Antia and Basu (2006) from higher degree modes using the dimensionless sound speed derivative in the solar convection zone.…”

Section: Discussionsupporting

confidence: 53%

Sensitivity of the sub-photospheric flow fields inferred from ring-diagram analysis to the change on the solar model

Zaatri

Provost

Corbard

et al. 2009

Astrophys Space Sci

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Context. The most recent determination of the solar chemical composition, using a time-dependent, 3D hydrodynamical model of the solar atmosphere, exhibits a significant decrease of C, N, O abundances compared to their previous values. Solar models that use these new abundances are not consistent with helioseismological determinations of the sound speed profile, the surface helium abundance and the convection zone depth. Aims. We investigate the effect of changes of solar abundances on low degree p-mode and g-mode characteristics which are strong constraints of the solar core. We consider particularly the increase of neon abundance in the new solar mixture in order to reduce the discrepancy between models using new abundances and helioseismology. Methods. The observational determinations of solar frequencies from the GOLF instrument are used to test solar models computed with different chemical compositions. We consider in particular the normalized small frequency spacings in the low degree p-mode frequency range. Results. Low-degree small frequency spacings are very sensitive to changes in the heavy-element abundances, notably neon. We show that by considering all the seismic constraints, including the small frequency spacings, a rather large increase of neon abundance by about (0.5 ± 0.05)dex can be a good solution to the discrepancy between solar models that use new abundances and low degree helioseismology, subject to adjusting slightly the solar age and the highest abundances. We also show that the change in solar abundances, notably neon, considerably affects g-mode frequencies, with relative frequency differences between the old and the new models higher than 1.5%.

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Section: Discussionsupporting

confidence: 53%

Sensitivity of the sub-photospheric flow fields inferred from ring-diagram analysis to the change on the solar model

Zaatri

Provost

Corbard

et al. 2009

Astrophys Space Sci

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“…As a consequence of adopting these new abundances for calculating solar opacities, one finds that these opacities are no longer compatible with the ones derived from helioseismological observations (Bahcall et al 2005;Antia & Basu 2006). In another recent article, Bochsler et al (2006) have argued that solar abundances inferred from solar wind measurements for oxygen and neon are also incompatible with the new values given by Asplund et al (2005).…”

Section: Introductionmentioning

confidence: 82%

Solar abundances of oxygen and neon derived from solar wind observations

Bochsler¹

2007

A&A

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Context. Recently, a revision of the solar abundances of C, N, and O to substantially lower values has led to a controversy on solar opacities in the solar standard model and to the suggestion to revise the solar abundance of neon upward by as much as a factor of 1.6 leading to enhanced solar neon/oxygen abundance ratios by a factor of 3. Neon and oxygen are neighboring elements with easily defined charged states in the solar wind, and they have been well identified and measured for over two decades in the solar wind under many circumstances and with several instruments. The solar wind Ne/O ratio is 0.14 with a conservative error estimate of ±0.03, consistent with the coronal value derived from solar energetic particle measurements. Aims. We investigate, whether solar wind observations are consistent with the newly proposed elemental solar abundances of neon and oxygen. Methods. The solar helium abundance has been derived from helioseismological observations. Helium and neon abundances in the solar wind have been well determined with the Apollo Foil experiments and, more recently, confirmed with the Genesis sample return mission. With these observations and the neon/oxygen solar wind abundance ratio determined by in-situ mass-spectrometry and using a simple theoretical model of Coulomb-drag fractionation for the solar wind, we estimate solar abundances for neon and oxygen. Results. From the variability of the helium/oxygen and the helium/neon ratio in the solar wind and from theoretical considerations, we conclude that the helium/neon ratio in the outer solar convective zone is 900 ± 110. Our best estimates of the solar neon and oxygen abundances in logarithmic dex-units are [Ne] = 7.96 ± 0.13, and [O] = 8.87 ± 0.11. Conclusions. Our solar neon/oxygen abundance ratio is consistent with the ratio derived from EUV-spectra from SOHO/CDS. However, our absolute abundance for oxygen is only marginally compatible with the newly derived value for oxygen, and our neon value is clearly incompatible with the recently proposed enhancement of the solar neon abundance.

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“…These values are definitely higher than any of the values in Table 5. From the solar sound-speed profile, Antia & Basu (2006) derive Z = 0.0172 ± 0.002. Again, this value is higher than any value in Table 5, even though it is within 2σ of the highest value in the table.…”

Section: Metallicity From Helioseismologymentioning

confidence: 97%

“…Helioseismology can provide a measurement of the solar metallicity in essentially three ways: i) from the depth of the convection zone: this depends sensitively on the opacity at the base of the convection zone, which in turn is a function of the abundance of heavy elements (Basu & Antia 1997); ii) using information from the core: the small-frequency spacings of low-degree modes and their separation ratios are sensitive to the mean molecular weight in the core, which can be related to the metallicity of the outer layers ); iii) from the sound speed gradient in the ionisation zone: the depth profile of this quantity can be inferred from helioseismic inversions, and comparison with the results of theoretical solar structure models of different metallicity allows us to place tight constraints on Z (Antia & Basu 2006). A comprehensive review on helioseismology and solar abundances is given by Basu & Antia (2008) which the reader is referred to for further details.…”

Section: Introductionmentioning

confidence: 99%

The solar photospheric nitrogen abundance

Caffau¹,

Maiorca

Bonifacio

et al. 2009

A&A

136

128

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Context. In recent years, the solar chemical abundances have been studied in considerable detail because of discrepant values of solar metallicity inferred from different indicators, i.e., on the one hand, the "sub-solar" photospheric abundances resulting from spectroscopic chemical composition analyses with the aid of 3D hydrodynamical models of the solar atmosphere, and, on the other hand, the high metallicity inferred by helioseismology. Aims. After investigating the solar oxygen abundance using a CO 5 BOLD 3D hydrodynamical solar model in previous work, we undertake a similar approach studying the solar abundance of nitrogen, since this element accounts for a significant fraction of the overall solar metallicity, Z. Methods. We used a selection of atomic spectral lines to determine the solar nitrogen abundance, relying mainly on equivalent width measurements in the literature. We investigate the influence on the abundance analysis, of both deviations from local thermodynamic equilibrium ("NLTE effects") and photospheric inhomogeneities ("granulation effects"). Results. We recommend use of a solar nitrogen abundance of A(N) = 7.86 ± 0.12 , whose error bar reflects the line-to-line scatter. Conclusions. The solar metallicity implied by the CO 5 BOLD-based nitrogen and oxygen abundances is in the range 0.0145 ≤ Z ≤ 0.0167. This result is a step towards reconciling photospheric abundances with helioseismic constraints on Z. Our most suitable estimates are Z = 0.0156 and Z/X = 0.0213.

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Determining Solar Abundances Using Helioseismology

Cited by 96 publications

References 39 publications

Sensitivity of the sub-photospheric flow fields inferred from ring-diagram analysis to the change on the solar model

Sensitivity of the sub-photospheric flow fields inferred from ring-diagram analysis to the change on the solar model

Solar abundances of oxygen and neon derived from solar wind observations

The solar photospheric nitrogen abundance

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