| Issue |
A&A
Volume 681, January 2024
|
|
|---|---|---|
| Article Number | A57 | |
| Number of page(s) | 15 | |
| Section | The Sun and the Heliosphere | |
| DOI | https://doi.org/10.1051/0004-6361/202346928 | |
| Published online | 11 January 2024 | |
Helioseismic determination of the solar metal mass fraction⋆
1
Département d’Astronomie, Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland
e-mail: gael.Buldgen@unige.ch
2
STAR Institute, Université de Liège, Liège, Belgium
3
Sternberg Astronomical Institute, Lomonosov Moscow State University, 119234 Moscow, Russia
4
Theoretical Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516 751 20 Uppsala, Sweden
5
Centre Spatial de Liège, Université de Liège, Angleur-Liège, Belgium
Received:
17
May
2023
Accepted:
24
August
2023
Context. The metal mass fraction of the Sun Z is a key constraint in solar modelling, but its value is still under debate. The standard solar chemical composition of the late 2000s has the ratio of metals to hydrogen as Z/X = 0.0181, and there was a small increase to 0.0187 in 2021, as inferred from 3D non-LTE spectroscopy. However, more recent work on a horizontally and temporally averaged ⟨3D⟩ model claim Z/X = 0.0225, which is consistent with the high values based on 1D LTE spectroscopy from 25 years ago.
Aims. We aim to determine a precise and robust value of the solar metal mass fraction from helioseismic inversions, thus providing independent constraints from spectroscopic methods.
Methods. We devised a detailed seismic reconstruction technique of the solar envelope, combining multiple inversions and equations of state in order to accurately and precisely determine the metal mass fraction value.
Results. We show that a low value of the solar metal mass fraction corresponding to Z/X = 0.0187 is favoured by helioseismic constraints and that a higher metal mass fraction corresponding to Z/X = 0.0225 is strongly rejected by helioseismic data.
Conclusions. We conclude that direct measurement of the metal mass fraction in the solar envelope favours a low metallicity, in line with the 3D non-LTE spectroscopic determination of 2021. A high metal mass fraction, as measured using a ⟨3D⟩ model in 2022, is disfavoured by helioseismology for all modern equations of state used to model the solar convective envelope.
Key words: Sun: helioseismology / Sun: oscillations / Sun: fundamental parameters / Sun: abundances
Full dataset is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/681/A57
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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