Stable magnetic fields in stellar interiors

Braithwaite, Jonathan; Nordlund, Åke

doi:10.1051/0004-6361:20041980

Cited by 367 publications

(499 citation statements)

References 29 publications

Supporting

Mentioning

461

Contrasting

Unclassified

Order By: Relevance

“…This analytical solution is thus similar to the axisymmetric non force-free relaxed solution family obtained by Braithwaite & Spruit (2004) and Braithwaite & Nordlund (2006). Its stability has now been demonstrated by Duez et al (2010a, see also Duez et al in this volume).…”

Section: Relaxed Non Force-free Configurationssupporting

confidence: 81%

“…It was suggested by Prendergast (1956) that a stellar magnetic field in stable axisymmetric equilibrium must contain both poloidal (meridional) and toroidal (azimuthal) components, since both are unstable on their own (Tayler 1973;Wright 1973). This was confirmed recently by numerical simulations by Braithwaite & Spruit (2004); Braithwaite & Nordlund (2006);Braithwaite (2008) who showed that initial stochastic helical fields evolve on an Alfvén timescale Dynamics of fossil magnetic fields in massive star interiors 161 into stable configurations: axisymmetric and non-axisymmetric mixed poloidal-toroidal fields were found. This phenomenon well known in plasma physics is a MHD turbulent relaxation (i.e.…”

Section: Introductionmentioning

confidence: 83%

“…Let us now compare this analytical configuration to those obtained using numerical simulations (see Braithwaite & Spruit 2004;Braithwaite & Nordlund 2006;Braithwaite 2008). Braithwaite and collaborators performed numerical magnetohydrodynamical simulations of the relaxation of an initially random magnetic field in a stably stratified star.…”

Section: Relaxed Non Force-free Configurationsmentioning

confidence: 99%

See 2 more Smart Citations

Dynamics of fossil magnetic fields in massive star interiors

Mathis

2010

Proc. IAU

View full text Add to dashboard Cite

Abstract. In this talk, I review the different MHD processes, which take place in massive star interiors. First, I describe MHD instabilities, which act on magnetic fields in stellar radiation zones, and the dynamo action in massive stars that give strong indications in favor of a fossil origin of the fields observed at the surface of these stars. Then, I discuss the study of MHD turbulent relaxation processes, which are now examined in stellar interiors, to describe initial conditions for fossil magnetic fields. Finally, I focus on the state of the art of the modeling of the interaction between differential rotation, fossil magnetic field, meridional circulation, and turbulence.

show abstract

Section: Relaxed Non Force-free Configurationssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 83%

Section: Relaxed Non Force-free Configurationsmentioning

confidence: 99%

See 1 more Smart Citation

Dynamics of fossil magnetic fields in massive star interiors

Mathis

2010

Proc. IAU

View full text Add to dashboard Cite

show abstract

“…Braithwaite & Spruit (2004) and Braithwaite & Nordlund (2006) have shown that the combination of the Cowling instability with rotation and meridional circulation may lead to major reorganisation of the internal flux. Similarly, theoretical computations suggest how atmospheric chemical peculiarities might develop and evolve with time through the main sequence phase, but so far these computations have not succeeded in reproducing observed abundance patterns in detail (Babel & Michaud 1991).…”

Section: Introductionmentioning

confidence: 99%

Searching for links between magnetic fields and stellar evolution

Landstreet¹,

Bagnulo²,

Andretta³

et al. 2007

A&A

181

249

View full text Add to dashboard Cite

Context. The evolution of magnetic fields in Ap stars during the main sequence phase is presently mostly unconstrained by observation because of the difficulty of assigning accurate ages to known field Ap stars. Aims. We are carrying out a large survey of magnetic fields in cluster Ap stars with the goal of obtaining a sample of these stars with well-determined ages. In this paper we analyse the information available from the survey as it currently stands. Methods. We select from the available observational sample the stars that are probably (1) cluster or association members and (2) magnetic Ap stars. For the stars in this subsample we determine the fundamental parameters T eff , L/L , and M/M . With these data and the cluster ages we assign both absolute age and fractional age (the fraction of the main sequence lifetime completed). For this purpose we have derived new bolometric corrections for Ap stars. Results. Magnetic fields are present at the surfaces of Ap stars from the ZAMS to the TAMS. Statistically for the stars with M > 3 M the fields decline with advancing age approximately as expected from flux conservation together with increased stellar radius, or perhaps even faster than this rate, on a time scale of about 3 × 10 7 yr. In contrast, lower mass stars show no compelling evidence for field decrease even on a timescale of several times 10 8 yr. Conclusions. Study of magnetic cluster stars is now a powerful tool for obtaining constraints on evolution of Ap stars through the main sequence. Enlarging the sample of known cluster magnetic stars, and obtaining more precise rms fields, will help to clarify the results obtained so far. Further field observations are in progress.

show abstract

“…One possibility is that, at the end of the MS and its associated dynamo, the magnetic field is able to evolve into a stable configuration only in ≈50% of the cases. The evolution of magnetic fields into stable magnetic configurations has been studied (Braithwaite & Nordlund 2006), but it is difficult to make detailed predictions as the outcome depends on the complex initial conditions of the magnetic configuration left by turbulent convection, in particular magnetic energy and helicity (Braithwaite 2008). Moreover, these theoretical calculations do not include a compositional stratification, which instead might play an important role in confining the magnetic field after dynamo action ceases in the convective cores of stars.…”

mentioning

confidence: 99%

Asteroseismic Signatures of Evolving Internal Stellar Magnetic Fields

Cantiello

Fuller

Bildsten

2016

ApJ

View full text Add to dashboard Cite

Recent asteroseismic analyses indicate the presence of strong (B  10 5 G) magnetic fields in the cores of many red giant stars. Here, we examine the implications of these results for the evolution of stellar magnetic fields, and we make predictions for future observations. Those stars with suppressed dipole modes indicative of strong core fields should exhibit moderate but detectable quadrupole mode suppression. The long magnetic diffusion times within stellar cores ensure that dynamo-generated fields are confined to mass coordinates within the main-sequence (MS) convective core, and the observed sharp increase in dipole mode suppression rates above 1.5 M e is likely explained by the larger convective core masses and faster rotation of these more massive stars. In clump stars, core fields of ∼10 5 G can suppress dipole modes, whose visibility should be equal to or less than the visibility of suppressed modes in ascending red giants. High dipole mode suppression rates in low-mass (M  2 M e ) clump stars would indicate that magnetic fields generated during the MS can withstand subsequent convective phases and survive into the compact remnant phase. Finally, we discuss implications for observed magnetic fields in white dwarfs and neutron stars, as well as the effects of magnetic fields in various types of pulsating stars.

show abstract

Stable magnetic fields in stellar interiors

Cited by 367 publications

References 29 publications

Dynamics of fossil magnetic fields in massive star interiors

Dynamics of fossil magnetic fields in massive star interiors

Searching for links between magnetic fields and stellar evolution

Asteroseismic Signatures of Evolving Internal Stellar Magnetic Fields

Contact Info

Product

Resources

About