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The Impact of a Fossil Magnetic Field on Dipolar Mixed-Mode Frequencies in Sub- and Red-Giant Stars
- Source :
- Dynamics of the Sun and Stars. Honoring the Life and Work of Michael J. Thompson, Dynamics of the Sun and Stars. Honoring the Life and Work of Michael J. Thompson, Sep 2019, NCAR, Boulder, Colorado, USA, United States. pp.251, ⟨10.1007/978-3-030-55336-4_33⟩, Dynamics of the Sun and Stars-Honoring the Life and Work of Michael J. Thompson, Astrophysics and Space Science Proceedings ISBN: 9783030553357, Astrophysics and Space Science Proceedings, Astrophysics and Space Science Proceedings-Dynamics of the Sun and Stars
- Publication Year :
- 2019
- Publisher :
- HAL CCSD, 2019.
-
Abstract
- Stars more massive than $\sim 1.3$ M$_\odot$ are known to develop a convective core during the main-sequence: the dynamo process triggered by this convection could be the origin of a strong magnetic field inside the core of the star, trapped when it becomes stably stratified and for the rest of its evolution. The presence of highly magnetized white dwarfs strengthens the hypothesis of buried fossil magnetic fields inside the core of evolved low-mass stars. If such a fossil field exists, it should affect the mixed modes of red giants as they are sensitive to processes affecting the deepest layers of these stars. The impact of a magnetic field on dipolar oscillations modes was one of Pr. Michael J. Thompson's research topics during the 90s when preparing the helioseismic SoHO space mission. As the detection of gravity modes in the Sun is still controversial, the investigation of the solar oscillation modes did not provide any hint of the existence of a magnetic field in the solar radiative core. Today we have access to the core of evolved stars thanks to the asteroseismic observation of mixed modes from CoRoT, Kepler, K2 and TESS missions. The idea of applying and generalizing the work done for the Sun came from discussions with Pr. Michael Thompson in early 2018 before we loss him. Following the path we drew together, we theoretically investigate the effect of a stable axisymmetric mixed poloidal and toroidal magnetic field, aligned with the rotation axis of the star, on the mixed modes frequencies of a typical evolved low-mass star. This enables us to estimate the magnetic perturbations to the eigenfrequencies of mixed dipolar modes, depending on the magnetic field strength and the evolutionary state of the star. We conclude that strong magnetic fields of $\sim$ 1MG should perturbe the mixed-mode frequency pattern enough for its effects to be detectable inside current asteroseismic data.<br />Comment: Conference proceeding, in press, 7 pages, 3 figures
- Subjects :
- Physics
Field (physics)
010308 nuclear & particles physics
Oscillation
Red giant
White dwarf
FOS: Physical sciences
Astrophysics
01 natural sciences
Magnetic field
Dipole
Stars
Astrophysics - Solar and Stellar Astrophysics
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
Astrophysics::Earth and Planetary Astrophysics
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
Astrophysics::Galaxy Astrophysics
Dynamo
Subjects
Details
- Language :
- English
- ISBN :
- 978-3-030-55335-7
978-3-030-55336-4 - ISSN :
- 15706591 and 15706605
- ISBNs :
- 9783030553357 and 9783030553364
- Database :
- OpenAIRE
- Journal :
- Dynamics of the Sun and Stars. Honoring the Life and Work of Michael J. Thompson, Dynamics of the Sun and Stars. Honoring the Life and Work of Michael J. Thompson, Sep 2019, NCAR, Boulder, Colorado, USA, United States. pp.251, ⟨10.1007/978-3-030-55336-4_33⟩, Dynamics of the Sun and Stars-Honoring the Life and Work of Michael J. Thompson, Astrophysics and Space Science Proceedings ISBN: 9783030553357, Astrophysics and Space Science Proceedings, Astrophysics and Space Science Proceedings-Dynamics of the Sun and Stars
- Accession number :
- edsair.doi.dedup.....da56c92a41dd2c19562dd88b6159adfe
- Full Text :
- https://doi.org/10.1007/978-3-030-55336-4_33⟩