Magnetic Fields in Young Galaxies

Nordlund, Åke; Rögnvaldsson, Ö. E.

doi:10.1017/s1539299600014726

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…The outer layers which were included in the simulations and in which a superadiabatic gradient exist, are the most sensitive to the convection model. These simulations reproduced the granulation pattern of convective streams of solar convection, as well as the heat flux and spectrum (Spruit et al 1990, Nordlund & Stein 1995, Nordlund et al 1996, Kim et al 1996, Abbett et al 1997, Demarque et al 1997. Comparison of various measurements form the simulations (such as maximal temperature gradient near the outer boundary) enables calibration of the MLT parameter.…”

Section: Introductionmentioning

confidence: 73%

Calibrating the Mixing‐Length Parameter for a Red Giant Envelope

Asida¹

2000

ApJ

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Two-dimensional hydrodynamical simulations were made to calibrate the mixing length parameter for modeling red giant's convective envelope. As was briefly reported in Asida & Tuchman 1997, a comparison of simulations starting with models integrated with different values of the mixing length parameter, has been made. In this paper more results are presented, including tests of the spatial resolution and Large Eddy Simulation terms used by the numerical code. The consistent value of the mixing length parameter was found to be 1.4, for a red giant of mass 1.2M ⊙ , core mass of 0.96M ⊙ , luminosity of 200L ⊙ , and metallicity Z = 0.001.Subject headings: convection -methods: numerical -stars: AGB and post-AGB -stars: atmosphere Alternatives to the usual mixing length used in MLT (which is a free parameter times

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Section: Introductionmentioning

confidence: 73%

Calibrating the Mixing‐Length Parameter for a Red Giant Envelope

Asida¹

2000

ApJ

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“…Another possibility is that the primordial field is not tightly wound up because turbulent diffusion compensates for the winding due to shear [522]. In this case there would be a balance between shear and turbulent diffusion, and from the toroidal part of Eq.…”

Section: Observational Evidence For Dynamo Actionmentioning

confidence: 99%

Astrophysical magnetic fields and nonlinear dynamo theory

2005

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The current understanding of astrophysical magnetic fields is reviewed, focusing on their generation and maintenance by turbulence. In the astrophysical context this generation is usually explained by a self-excited dynamo, which involves flows that can amplify a weak 'seed' magnetic field exponentially fast. Particular emphasis is placed on the nonlinear saturation of the dynamo. Analytic and numerical results are discussed both for small scale dynamos, which are completely isotropic, and for large scale dynamos, where some form of parity breaking is crucial. Central to the discussion of large scale dynamos is the so-called alpha effect which explains the generation of a mean field if the turbulence lacks mirror symmetry, i.e. if the flow has kinetic helicity. Large scale dynamos produce small scale helical fields as a waste product that quench the large scale dynamo and hence the alpha effect. With this in mind, the microscopic theory of the alpha effect is revisited in full detail and recent results for the loss of helical magnetic fields are reviewed.Comment: 285 pages, 72 figures, accepted by Phys. Re

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Magnetic Fields in Young Galaxies

Cited by 2 publications

References 6 publications

Calibrating the Mixing‐Length Parameter for a Red Giant Envelope

Calibrating the Mixing‐Length Parameter for a Red Giant Envelope

Astrophysical magnetic fields and nonlinear dynamo theory

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