A self-consistent solar coronal heating model by Alfvenic waves

Abstract

Alfvenic waves are prevalent throughout the solar atmosphere and are believed to play an essential role in coronal heating, classified as alternating current (AC) heating in contrast to direct current (DC) heating associated with quasi-static magnetic field line braiding. The relative importance of AC versus DC heating depends on the details of the photospheric driver and on the configuration of the magnetic field. Moreover, even if AC heating prevails, several wave dissipation mechanisms have been proposed, and which of them dominates remains unclear, as its efficiency depends on plasma compressibility and density inhomogeneity. We address these issues by performing three-dimensional radiative magnetohydrodynamic (MHD) simulations of a coronal loop spanning from the upper convection zone to the corona, which self-consistently capture many relevant physical processes. We find that the corona is predominantly heated by AC heating, with Alfven wave turbulence providing the primary contribution, accounting for at least 80% of the entire coronal heating in the present simulation. Our results strongly support the use of Alfven wave turbulence-based models employed in space weather and stellar activity research, such as the Alfven Wave Solar Model (AWSoM) and the Magnetohydrodynamic Algorithm outside a Sphere (MAS).