---
_id: '11605'
abstract:
- lang: eng
text: "Context. The discovery of moderate differential rotation between the core
and the envelope of evolved solar-like stars could be the signature of a strong
magnetic field trapped inside the radiative interior. The population of intermediate-mass
red giants presenting surprisingly low-amplitude mixed modes (i.e. oscillation
modes that behave as acoustic modes in their external envelope and as gravity
modes in their core) could also arise from the effect of an internal magnetic
field. Indeed, stars more massive than about 1.1 solar masses are known to develop
a convective core during their main sequence. The field generated by the dynamo
triggered by this convection could be the progenitor of a strong fossil magnetic
field trapped inside the core of the star for the remainder of its evolution.\r\n\r\nAims.
Observations of mixed modes can constitute an excellent probe of the deepest layers
of evolved solar-like stars, and magnetic fields in those regions can impact their
propagation. The magnetic perturbation on mixed modes may therefore be visible
in asteroseismic data. To unravel which constraints can be obtained from observations,
we theoretically investigate the effects of a plausible mixed axisymmetric magnetic
field with various amplitudes on the mixed-mode frequencies of evolved solar-like
stars.\r\n\r\nMethods. First-order frequency perturbations due to an axisymmetric
magnetic field were computed for dipolar and quadrupolar mixed modes. These computations
were carried out for a range of stellar ages, masses, and metallicities.\r\n\r\nConclusions.
We show that typical fossil-field strengths of 0.1 − 1 MG, consistent with the
presence of a dynamo in the convective core during the main sequence, provoke
significant asymmetries on mixed-mode frequency multiplets during the red giant
branch. We provide constraints and methods for the detectability of such magnetic
signatures. We show that these signatures may be detectable in asteroseismic data
for field amplitudes small enough for the amplitude of the modes not to be affected
by the conversion of gravity into Alfvén waves inside the magnetised interior.
Finally, we infer an upper limit for the strength of the field and the associated
lower limit for the timescale of its action in order to redistribute angular momentum
in stellar interiors."
article_number: A53
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Lisa Annabelle
full_name: Bugnet, Lisa Annabelle
id: d9edb345-f866-11ec-9b37-d119b5234501
last_name: Bugnet
orcid: 0000-0003-0142-4000
- first_name: V.
full_name: Prat, V.
last_name: Prat
- first_name: S.
full_name: Mathis, S.
last_name: Mathis
- first_name: A.
full_name: Astoul, A.
last_name: Astoul
- first_name: K.
full_name: Augustson, K.
last_name: Augustson
- first_name: R. A.
full_name: García, R. A.
last_name: García
- first_name: S.
full_name: Mathur, S.
last_name: Mathur
- first_name: L.
full_name: Amard, L.
last_name: Amard
- first_name: C.
full_name: Neiner, C.
last_name: Neiner
citation:
ama: 'Bugnet LA, Prat V, Mathis S, et al. Magnetic signatures on mixed-mode frequencies:
I. An axisymmetric fossil field inside the core of red giants. Astronomy &
Astrophysics. 2021;650. doi:10.1051/0004-6361/202039159'
apa: 'Bugnet, L. A., Prat, V., Mathis, S., Astoul, A., Augustson, K., García, R.
A., … Neiner, C. (2021). Magnetic signatures on mixed-mode frequencies: I. An
axisymmetric fossil field inside the core of red giants. Astronomy & Astrophysics.
EDP Sciences. https://doi.org/10.1051/0004-6361/202039159'
chicago: 'Bugnet, Lisa Annabelle, V. Prat, S. Mathis, A. Astoul, K. Augustson, R.
A. García, S. Mathur, L. Amard, and C. Neiner. “Magnetic Signatures on Mixed-Mode
Frequencies: I. An Axisymmetric Fossil Field inside the Core of Red Giants.” Astronomy
& Astrophysics. EDP Sciences, 2021. https://doi.org/10.1051/0004-6361/202039159.'
ieee: 'L. A. Bugnet et al., “Magnetic signatures on mixed-mode frequencies:
I. An axisymmetric fossil field inside the core of red giants,” Astronomy &
Astrophysics, vol. 650. EDP Sciences, 2021.'
ista: 'Bugnet LA, Prat V, Mathis S, Astoul A, Augustson K, García RA, Mathur S,
Amard L, Neiner C. 2021. Magnetic signatures on mixed-mode frequencies: I. An
axisymmetric fossil field inside the core of red giants. Astronomy & Astrophysics.
650, A53.'
mla: 'Bugnet, Lisa Annabelle, et al. “Magnetic Signatures on Mixed-Mode Frequencies:
I. An Axisymmetric Fossil Field inside the Core of Red Giants.” Astronomy &
Astrophysics, vol. 650, A53, EDP Sciences, 2021, doi:10.1051/0004-6361/202039159.'
short: L.A. Bugnet, V. Prat, S. Mathis, A. Astoul, K. Augustson, R.A. García, S.
Mathur, L. Amard, C. Neiner, Astronomy & Astrophysics 650 (2021).
date_created: 2022-07-18T12:10:59Z
date_published: 2021-06-07T00:00:00Z
date_updated: 2022-08-19T10:06:33Z
day: '07'
doi: 10.1051/0004-6361/202039159
extern: '1'
external_id:
arxiv:
- '2102.01216'
intvolume: ' 650'
keyword:
- Space and Planetary Science
- Astronomy and Astrophysics
- stars
- oscillations / stars
- magnetic field / stars
- interiors / stars
- evolution / stars
- rotation
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/2102.01216
month: '06'
oa: 1
oa_version: Preprint
publication: Astronomy & Astrophysics
publication_identifier:
eissn:
- 1432-0746
issn:
- 0004-6361
publication_status: published
publisher: EDP Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Magnetic signatures on mixed-mode frequencies: I. An axisymmetric fossil field
inside the core of red giants'
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 650
year: '2021'
...