Stable magnetic fields in stellar interiors

By J. Braithwaite, Åke Nordlund. 2005

288 citations recorded by the source corpus.

We investigate the 50-year old hypothesis that the magnetic fields of the Ap stars are stable equilibria that have survived in these stars since their formation. With numerical simulations we find that stable magnetic field configurations indeed appear to exist under the conditions in the radiative interior of a star. Confirming a hypothesis by Prendergast (1956, ApJ, 123, 498), the configurations have roughly equal poloidal and toroidal field strengths. We find that tori of such twisted fields can form as remnants of the decay of an unstable random initial field. In agreement with observations, the appearance at the surface is an approximate dipole with smaller contributions from higher multipoles, and the surface field strength can increase with the age of the star. The results of this paper were summarised by Braithwaite & Spruit (2004, Nature, 431, 891).

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0241013f3706bc4ecd920e9d7e599835ad9ba942

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In Astronomy and Astrophysics

1. F. Najarro
2. J. Vink
3. P. Lasky
4. J. Landstreet
5. Paul Charbonneau
6. J. Braithwaite
7. J. Donati
8. J. Puls

Citations in the corpus

• Solar Dynamo Theory (2014, background): “Large-scale magnetic fields imbedded in stably stratified stellar interiors are known to be sensitive to an astoundingly wide range of instabilities (see, e.g., Pitts & Tayler 1985, Spruit 1999, Braithwaite & Nordlund 2006).”
• Gravitational Waves from Neutron Stars: A Review (2015, background): “…more applicable to main-sequence stars than to neutron stars), Braithwaite and co. showed magnetic fields evolve either to axisymmetric, twisted-tori (Braithwaite & Nordlund 2006; Braithwaite 2009), or nonaxisymmetric configurations (Braithwaite 2008), depending on the initial conditions.”
• Mass loss from hot massive stars (2008, background): “It has been shown by Moss (2001), Braithwaite and Spruit (2004) and Braithwaite and Nordlund (2006) that a dynamically stable configuration of such fossil fields on long time-scales is actually possible.”
• Axisymmetric magnetic fields in stars: relative strengths of poloidal and toroidal components (2008, methodology): “Numerical simulations (Braithwaite & Nordlund 2006, hereaft r Paper I; see also Braithwaite & Spruit 2004) showed that an arbitrary initial magnetic field inside a non-convective star can evolve on an Alfvén timescale into a stable configuration.”
• The surprising magnetic topology of τ Sco: fossil remnant or dynamo output? (2006, unknown): “…no intrinsic variability on timescales of decades. c (cid:13) 0000 RAS, MNRAS 000 , 000–000 Recent numerical results by Braithwaite & Spruit (2004) and Braithwaite & Nordlund (2006) also indicate that magnetic fields in hot stars seem to reach a stable equilibrium (involving both potential and…”
• Magnetic Fields of Nondegenerate Stars (2009, background): “Recent numerical experiments (Braithwaite & Spruit 2004; Braithwaite & Nordlund 2006) suggested that many initially unstable global field topologies spontaneously develop such a mixed poloidal/toroidal field configuration and become stable in doing so.”