Magneto-Rotational Transport in the Early Sun

Abstract

Angular momentum transport must have occurred in the Sun's radiative zone to explain its current solid body rotation. We survey the stability of the early Sun's radiative zone with respect to diffusive rotational instabilities, for a variety of plausible past configurations. We find that the (faster rotating) early Sun was prone to rotational instabilities even if only weak levels of radial differential rotation were present, while the current Sun is not. Stability domains are determined by approximate balance between dynamical and diffusive timescales, allowing generalizations to other stellar contexts. Depending on the strength and geometry of the weak magnetic field present, the fastest growing unstable mode can be hydrodynamic or magneto-hydrodynamic (MHD) in nature. Our results suggest that diffusive MHD modes may be more efficient at transporting angular momentum than their hydrodynamic (``Goldreich-Schubert-Fricke'') counterparts because the minimum spatial scale required for magnetic tension to be destabilizing limits the otherwise very small scales favored by double-diffusive instabilities. Diffusive magneto-rotational instabilities are thus attractive candidates for angular momentum transport in the early Sun's radiative zone.

arXiv comment23 pages, 4 figures, accepted for publication in ApJ

References in corpus (17)

• Collapsars - Gamma-Ray Bursts and Explosions in "Failed Supernovae"
• Dynamo action by differential rotation in a stably stratified stellar interior
• Solar Models: current epoch and time dependences, neutrinos, and helioseismological properties
• Presupernova Evolution of Differentially Rotating Massive Stars Including Magnetic Fields
• Influence of gravity waves on the internal rotation and Li abundance of solar-type stars
• Stellar Models with Microscopic Diffusion and Rotational Mixing I: Application to the Sun
• The Spin Periods and Rotational Profiles of Neutron Stars at Birth
• Stellar Evolution with Rotation and Magnetic Fields IV: The Solar Rotation Profile
• Angular momentum extraction by gravity waves in the Sun
• Stellar Models with Microscopic Diffusion and Rotational Mixing II: Application to Open Clusters
• Transport and mixing in the radiation zones of rotating stars II. Axisymmetric magnetic field
• Angular momentum transport by gravity waves and its effect on the rotation of the solar interior
• Gravity Waves in the Sun
• Local Axisymmetric Diffusive Stability of Weakly-Magnetized, Differentially-Rotating, Stratified Fluids
• Bounds on the Magnetic Fields in the Radiative Zone of the Sun
• Radiative zone solar magnetic fields and g-modes
• Differential Rotation in Weakly-Magnetized Neutron Star Atmospheres

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