2006/06/14 by Kristen Menou, Joel LeMer, Joel Le Mer · 15 citations
Physics and Astronomy · #Angular momentum #Astrophysics and Star Formation Studies #Differential rotation #Magnetic field #Magnetohydrodynamics #Magnetorotational instability #Momentum (technical analysis) #Radiative transfer #Rotation (mathematics) #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/507022
published in The Astrophysical Journal 650(2), 1208-1216 (IOP Publishing) · 23 pages, 4 figures, accepted for publication in ApJ
arxiv created 2006/06/14 · openalex publication_date 2006/10/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 magnetohydrodynamic (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 magnetorotational instabilities are thus attractive candidates for angular momentum transport in the early Sun's radiative zone.