Propagating MHD waves in coronal holes

TL;DR

This paper reviews observational evidence of propagating MHD waves in coronal holes, discussing their characteristics and role in solar wind acceleration and coronal heating.

Contribution

It provides a comprehensive overview of observed MHD wave properties in coronal holes and their implications for solar wind models.

Findings

Detection of propagating MHD waves in coronal holes

Wave characteristics constrain theoretical models

Waves likely contribute to solar wind acceleration

Abstract

Coronal holes are the coolest and darkest regions of the solar atmosphere, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. During the years of the solar minima, coronal holes are generally confined to the Sun's polar regions, while at solar maxima they can also be found at lower latitudes. Waves, observed via remote sensing and detected in-situ in the wind streams, are most likely responsible for the wind and several theoretical models describe the role of MHD waves in the acceleration of the fast solar wind. This paper reviews the observational evidences of detection of propa- gating waves in these regions. The characteristics of the waves, like periodicities, amplitude, speed provide input parameters and also act as constraints on theoretical models of coronal heating and solar wind acceleration.