A Model of Magnetic Braking of Solar Rotation That Satisfies Observational Constraints

TL;DR

This paper presents a refined model of magnetic braking in solar rotation that accurately reproduces the rotational evolution of solar-type stars across different ages and rotation speeds, aligning with multiple observational constraints.

Contribution

The model introduces anisotropic turbulent diffusion and accounts for poloidal field decay, improving upon previous models to match diverse observational data.

Findings

Successfully reproduces rotational evolution of both fast and slow rotators.

Aligns with observed Li abundance evolution in solar twins.

Maintains the thinness of the solar tachocline.

Abstract

The model of magnetic braking of solar rotation considered by Charbonneau & MacGregor (1993) has been modified so that it is able to reproduce for the first time the rotational evolution of both the fastest and slowest rotators among solar-type stars in open clusters of different ages, without coming into conflict with other observational constraints, such as the time evolution of the atmospheric Li abundance in solar twins and the thinness of the solar tachocline. This new model assumes that rotation-driven turbulent diffusion, which is thought to amplify the viscosity and magnetic diffusivity in stellar radiative zones, is strongly anisotropic with the horizontal components of the transport coefficients strongly dominating over those in the vertical direction. Also taken into account is the poloidal field decay that helps to confine the width of the tachocline at the solar age. The model's properties are investigated by numerically solving the azimuthal components of the coupled momentum and magnetic induction equations in two dimensions using a finite element method