The Quiet-Sun Photosphere and Chromosphere

TL;DR

This paper reviews the current understanding of the solar photosphere and chromosphere, highlighting recent advances in modeling and the remaining challenges in understanding small-scale dynamical processes and magnetic features.

Contribution

It provides a comprehensive overview of recent progress in 3D MHD simulations of the photosphere and discusses the ongoing challenges in modeling the chromosphere's complex dynamics.

Findings

3D MHD simulations improve understanding of the photosphere.

Chromosphere remains less understood due to complex small-scale processes.

Open-field features are more promising for future research.

Abstract

The overall structure and the fine structure of the solar photosphere outside active regions are largely understood, except possibly important roles of a turbulent near-surface dynamo at its bottom, internal gravity waves at its top, and small-scale vorticity. Classical 1D static radiation-escape modelling has been replaced by 3D time-dependent MHD simulations that come closer to reality. The solar chromosphere, in contrast, remains ill-understood although its pivotal role in coronal mass and energy loading makes it a principal research area. Its fine structure defines its overall structure, so that hard-to-observe and hard-to-model small-scale dynamical processes are the key to understanding. However, both chromospheric observation and chromospheric simulation presently mature towards the required sophistication. The open-field features seem of greater interest than the easier-to-see closed-field features.