Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main-sequence stars

Bhattacharya S, Das SB, Bugnet LA, Panda S, Hanasoge SM. 2024. Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main-sequence stars. Astrophysical Journal. 970(1), 42.

Download
OA 2024_AstrophysicalJourn_Bhattacharya.pdf 3.91 MB [Published Version]

Journal Article | Published | English

Scopus indexed
Author
Bhattacharya, Shatanik; Das, Srijan BISTA ; Bugnet, LisaISTA ; Panda, Subrata; Hanasoge, Shravan M.
Department
Abstract
Magnetic fields in the stellar interiors are key candidates to explain observed core rotation rates inside solar-like stars along their evolution. Recently, asteroseismic estimates of radial magnetic field amplitudes near the hydrogen-burning shell (H-shell) inside about 24 red giants (RGs) have been obtained by measuring frequency splittings from their power spectra. Using general Lorentz-stress (magnetic) kernels, we investigated the potential for detectability of near-surface magnetism in a 1.3 M⊙ star of supersolar metallicity as it evolves from a mid subgiant to a late subgiant into an RG. Based on these sensitivity kernels, we decompose an RG into three zones—deep core, H-shell, and near-surface. The subgiants instead required decomposition into an inner core, an outer core, and a near-surface layer. Additionally, we find that for a low-frequency g-dominated dipolar mode in the presence of a typical stable magnetic field, ∼25% of the frequency shift comes from the H-shell and the remaining from deeper layers. The ratio of the subsurface tangential field to the radial field in the H-burning shell decides if subsurface fields may be potentially detectable. For p-dominated dipole modes close to vmax, this ratio is around two orders of magnitude smaller in subgiant phases than the corresponding RG. Further, with the availability of magnetic kernels, we propose lower limits of field strengths in crucial layers in our stellar model during its evolutionary phases. The theoretical prescription outlined here provides the first formal way to devise inverse problems for stellar magnetism and can be seamlessly employed for slow rotators.
Publishing Year
Date Published
2024-07-15
Journal Title
Astrophysical Journal
Acknowledgement
This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 101034413. S. B.D. acknowledges Prof. Jeroen Tromp at Princeton University for supporting a part of this work. S.M.H., S.B., and S.P. acknowledge support from the Department of Atomic Energy, Government of India, under Project Identification No. RTI 4002. The authors would like to thank the reviewer(s) and data editor for their constructive comments and suggestions. The generation of the stellar models was done using the Modules for Experiments in Stellar Astrophysics (MESA Paxton et al. 2011, 2013, 2015, 2018, 2019; we have used MESA version r22.05.1 for RG and r23.05.1 for SG models, MESA-SDK version x86_64-linux-22.6.1). The eigenfrequencies and eigenfunctions for this model were calculated using the GYRE (Townsend & Teitler 2013) code. The code to calculate the kernels and the splittings has been written completely in Python 3.8.16.
Volume
970
Issue
1
Article Number
42
ISSN
eISSN
IST-REx-ID

Cite this

Bhattacharya S, Das SB, Bugnet LA, Panda S, Hanasoge SM. Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main-sequence stars. Astrophysical Journal. 2024;970(1). doi:10.3847/1538-4357/ad4708
Bhattacharya, S., Das, S. B., Bugnet, L. A., Panda, S., & Hanasoge, S. M. (2024). Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main-sequence stars. Astrophysical Journal. IOP Publishing. https://doi.org/10.3847/1538-4357/ad4708
Bhattacharya, Shatanik, Srijan B Das, Lisa Annabelle Bugnet, Subrata Panda, and Shravan M. Hanasoge. “Detectability of Axisymmetric Magnetic Fields from the Core to the Surface of Oscillating Post-Main-Sequence Stars.” Astrophysical Journal. IOP Publishing, 2024. https://doi.org/10.3847/1538-4357/ad4708.
S. Bhattacharya, S. B. Das, L. A. Bugnet, S. Panda, and S. M. Hanasoge, “Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main-sequence stars,” Astrophysical Journal, vol. 970, no. 1. IOP Publishing, 2024.
Bhattacharya S, Das SB, Bugnet LA, Panda S, Hanasoge SM. 2024. Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main-sequence stars. Astrophysical Journal. 970(1), 42.
Bhattacharya, Shatanik, et al. “Detectability of Axisymmetric Magnetic Fields from the Core to the Surface of Oscillating Post-Main-Sequence Stars.” Astrophysical Journal, vol. 970, no. 1, 42, IOP Publishing, 2024, doi:10.3847/1538-4357/ad4708.
All files available under the following license(s):
Creative Commons Attribution 4.0 International Public License (CC-BY 4.0):
Main File(s)
Access Level
OA Open Access
Date Uploaded
2024-07-29
MD5 Checksum
acb42a87deecbc9228fbbe6a48a37ec6


Export

Marked Publications

Open Data ISTA Research Explorer

Sources

arXiv 2404.17167

Search this title in

Google Scholar