Connecting the sun and the solar wind: The first 2.5-dimensional self-consistent MHD simulation under the ALFVN wave scenario

Abstract

The solar wind emanates from the hot and tenuous solar corona. Earlier studies using 1.5-dimensional simulations show that Alfvén waves generated in the photosphere play an important role in coronal heating through the process of nonlinear mode conversion. In order to understand the physics of coronal heating and solar wind acceleration together, it is important to consider the regions from photosphere to interplanetary space as a single system. We performed 2.5-dimensional, self-consistent magnetohydrodynamic simulations, covering from the photosphere to the interplanetary space for the first time. We carefully set up the grid points with spherical coordinates to treat the Alfvén waves in the atmosphere with huge density contrast and successfully simulate the solar wind streaming out from the hot solar corona as a result of the surface convective motion. The footpoint motion excites Alfvén waves along an open magnetic flux tube, and these waves traveling upward in the non-uniform medium undergo wave reflection, nonlinear mode conversion from Alfvén mode to slow mode, and turbulent cascade. These processes lead to the dissipation of Alfvén waves and acceleration of the solar wind. It is found that the shock heating by the dissipation of the slow-mode wave plays a fundamental role in the coronal heating process, whereas the turbulent cascade and shock heating drive the solar wind. © 2012 The American Astronomical Society. All rights reserved.