Magnetic Field Generation in Fully Convective Rotating Spheres

By Wolfgang Dobler, M. Stix, Axel Brandenburg. 2004

187 citations recorded by the source corpus.

Magnetohydrodynamic simulations of fully convective, rotating spheres with volume heating near the center and cooling at the surface are presented. The dynamo-generated magnetic field saturates at equipartition field strength near the surface. In the interior, the field is dominated by small-scale structures, but outside the sphere, by the global scale. Azimuthal averages of the field reveal a large-scale field of smaller amplitude also inside the star. The internal angular velocity shows some tendency to be constant along cylinders and is "antisolar" (fastest at the poles and slowest at the equator).

Subfields: Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/ca4e19daac69670c9edd8da606a76209fc31690e

How researchers see this paper

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In Astronomy and Astrophysics

1. A. Reiners
2. J. Donati
3. M. Gudel
4. J. Landstreet
5. G. Basri
6. K. Luhman
7. J. Morin
8. P. Petit

In Molecular Biology

1. T. Gastine
2. J. Landstreet
3. J. Donati
4. J. Doyle
5. S. Marsden
6. P. Petit
7. A. Reiners
8. G. Basri

Citations in the corpus

• Large-scale magnetic topologies of early M dwarfs (2008, background): “Many theoretical models were proposed to attempt resolving this issue (e.g., Durney et al. 1993; Dobler et al. 2006; Browning 2008) but observations of the large-scale magnetic fields at the surfaces of fullyconvective stars, and in particular of their poloidal and toroidal components, are still…”
• A VOLUME-LIMITED SAMPLE OF 63 M7–M9.5 DWARFS. II. ACTIVITY, MAGNETISM, AND THE FADE OF THE ROTATION-DOMINATED DYNAMO (2009, background): “Our understanding of purely turbulent dynamos is only at its beginning, but large progress was made during the last years (e.g., Durney et al. 1993; Dobler et al. 2006; Browning 2008).”
• Radio Observations of a Large Sample of Late M, L, and T Dwarfs: The Distribution of Magnetic Field Strengths (2006, result): “…magnetohydrodynamic simulations provide tantalizing evidence that a large-scale and stable field may in fact be generated (Chabrier & Küker 2006; Dobler et al. 2006), contrary to earlier indications (Durney et al. 1993), but initial observations suggest that themodels are not complete (Donati…”
• On magnetic instabilities and dynamo action in stellar radiation zones (2007, background): “Theory benefits enormously from these new constraints, and quite naturally the main focus is on the generation of magnetic fields in turbulent convection zones, which can now been studied through high resolution numerical simulations (Brun et al. 2004, 2005; Dobler et al. 2006).”
• Magnetospheric accretion on the T Tauri star BP Tauri (2008, background): “…fields of low-mass cTTS are likely dynamo-generated rather than fossil fields; the underlying processes capable of producing such fields almost without the help of differential rotation are not yet fully understood from a theoretical point of view (Chabrier & Küker 2006; Dobler et al. 2006).”
• Large-scale magnetic topologies of late M dwarfs★: Magnetic topologies of late M dwarfs (2010, background): “Subsequent direct numerical simulations by Dobler et al. (2006) and Browning (2008) both realized large-scale dynamo action with a significant axisymmetric component of the resulting magnetic field.”
• Large-scale magnetic topologies of late M dwarfs⋆ (2008, background): “…diagnose either “antisolar” differential rotation (i.e. poles faster than the equator) associated with a net axisymmetric poloidal field (e.g., Dobler et al. 2006); or strongly quenched “solar” differential rotation (i.e. the equator faster than the poles) and a strong axisymmetric toroidal…”
• The First Direct Measurements of Surface Magnetic Fields on Very Low Mass Stars (2006, background): “If the dynamo scale gets too small (as in the so-called fully turbulent dynamo), then rotation should not matter as much (Durney et al. 1993; Dobler et al. 2006).”
• Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs (2008, background): “…confirmed for ultracool dwarfs by Reiners & Basri (2007) as well as the large-scale, stable, magnetic fields predicted by current dynamo models and confirmed by observation for fully convective low mass objects (Dobler et al. 2006; Chabrier & Küker 2006; Donati et al. 2006; Browning 2007).”
• Magnetic Fields of Nondegenerate Stars (2009, background): “Dynamos in fully-convective M dwarfs are obviously capable of producing strong axisymmetric fields (Dobler et al. 2006; Browning 2008) and can presumably do the same in the core of upper main sequence stars (Charbonneau & MacGregor 2001; MacGregor & Cassinelli 2003; Brun et al. 2005).”
• X-ray emission from T Tauri stars and the role of accretion: inferences from the XMM-Newton extended survey of the Taurus molecular cloud (2006, background): “…are thought to be fully convective and hence unable to support a solar-like α-Ω dynamo, fullyconvective main-sequence stars do show magnetic activity, and dynamo mechanisms have been proposed that may operate in such stars (e.g., Dobler et al. 2006 and references therein; Küker & Rüdiger 1999).”
• The Magnetic Fields of Classical T Tauri Stars (2007, background): “Recent studies by Chabrier & Küker (2006) and Dobler et al. (2006) do predict that dynamo action in fully convective stars does correlate with rotation rate.”
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs (2008, background): “This suggestion has now run afoul of both observations (Donati et al. 2006) and theory (Dobler et al. 2006; Browning 2007).”