Coronal heating and solar wind formation in quiet Sun and coronal holes: a unified scenario

TL;DR

This study compares the transition region properties of coronal holes and quiet Sun regions using IRIS and SDO data, proposing a unified model for coronal heating and solar wind formation based on magnetic flux differences.

Contribution

It provides a comprehensive analysis of magnetic flux and spectral line shifts in CHs and QS, leading to a unified scenario for coronal heating and solar wind generation.

Findings

Si IV intensities are lower in CHs than in QS at the same magnetic flux.

Differences in intensities increase with magnetic flux.

QS shows more redshifted line profiles than CHs.

Abstract

Coronal holes (CHs) are darker than quiet Sun (QS) when observed in coronal channels. This study aims to understand the similarities and differences between CHs and QS in the transition region using the \ion{Si}{4}~1394~{\AA} line recorded by the Interface Region Imaging Spectrograph (IRIS) by considering the distribution of magnetic field measured by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We find that \ion{Si}{4} intensities obtained in CHs are lower than those obtained in QS for regions with identical magnetic flux densities. Moreover, the difference in intensities between CHs and QS increases with increasing magnetic flux. For the regions with equal magnetic flux density, QS line profiles are more redshifted than those measured in CHs. Moreover, the blue shifts measured in CHs show an increase with increasing magnetic flux density unlike in the QS. The non-thermal velocities in QS, as well as in CHs, show an increase with increasing magnetic flux. However, no significant difference was observed in QS and CHs, albeit a small deviation at small flux densities. Using these results, we propose a unified model for the heating of the corona in the QS and in CHs and the formation of the solar wind.