Angular Momentum Transport in the Sun’s Radiative Zone by Gravito-Inertial Waves

Abstract

Internal gravity waves constitute an efficient process for angular momentum transport over large distances. They are now seen as an important ingredient in understanding the evolution of stellar rotation and can explain the Sun's quasi-flat internal-rotation profile. Because the Sun's rotation frequency is of the same order as that of the waves, it is now necessary to refine our description of wave propagation and to take into account the action of the Coriolis acceleration in a coherent way. To achieve this goal, we adopt the traditional approximation, which can be applied to stellar radiation zones under conditions that are given. We present the modified transport equations and their numerical evaluation in a parameter range that is significant for the Sun. Consequences for the transport of angular momentum inside solar and stellar radiative regions are discussed.Helioseismology, Asteroseismology, and MHD Connections

Surface convection and red-giant radius measurements

“…The dynamics of the Sun radiation zone is largely uncertain as suggested by helioseismology (Turck-Chièze et al 2004). It probably involves angular momentum transport through internal waves (Charbonnel & Talon 2005;Mathis et al 2008). Moreover, the mixing of the radiative interior associated with rotation (as in the tachocline) interacts with diffusion along the evolution (Brun et al 1999).…”

Low-frequency internal waves in magnetized rotating stellar radiation zones

“…2.5). As shown in Mathis et al (2008) in the hydrodynamical case, this hypothesis allows us to separate the variables in the treatment of the adiabatic dynamical equations. This net variable separation becomes impossible for a general differential rotation law and azimuthal magnetic field (Ω (r, θ), Fig.…”

“…This is due to the choice to study in a first step the "weak differential rotation case" for which Ω s > > ΔΩ. This means that the impact of ΔΩ on θ c;m constitutes only a small correction that does not change its main behaviour (see Mathis et al 2008, in the hydrodynamical case). A general differential rotation in which the critical latitude explicitely depends on the angular rotation profile and on its vertical and latitudinal gradients has been studied in Mathis (2009) in the purely hydrodynamical case and will be studied in Paper III.…”

“…As in Mathis et al (2008), we only take into account the solidbody part of the rotation law (Ω s ) to derive the adiabatic wave structure, the small departure from it (ΔΩ) is only accounted for in the treatment of the dissipative mechanisms (Sect. 2.5).…”

“…As explained in Paper I, we proceed step by step to introduce the influence of the (differential) rotation and the magnetic field because of the complexity of the problem. As in Paper I, we chose to treat a purely axisymmetric toroidal field associated to a constant Alfvén frequency and a weak differential rotation (see Mathis et al 2008, for the hydrodynamical case) to isolate the properties of the induced transport as a function of the angular velocity value and the magnetic field amplitude. General differential rotations (Ω (r, θ); cf.…”