On the Probable Existence of an Abrupt Magnetization in the Upper Chromosphere of the Quiet Sun

TL;DR

This study uses radiative transfer modeling of H-alpha scattering polarization to suggest an abrupt increase in magnetic field strength in the upper quiet Sun chromosphere, impacting our understanding of solar heating.

Contribution

It provides the first detailed inference of a sharp magnetic transition in the quiet Sun's chromosphere using polarization data.

Findings

Magnetic field <B> > 30 G below the transition region

Weak magnetic field <B> ~ 1 G underneath

Implication for chromospheric and coronal heating

Abstract

We report on a detailed radiative transfer modeling of the observed scattering polarization in the H-alpha line, which allows us to infer quantitative information on the magnetization of the quiet solar chromosphere. Our analysis suggests the presence of a magnetic complexity zone with a mean field strength <B> > 30 G lying just below the sudden transition region to the coronal temperatures. The chromospheric plasma directly underneath is very weakly magnetized, with <B> ~ 1 G. The possible existence of this abrupt change in the degree of magnetization of the upper chromosphere of the quiet Sun might have large significance for our understanding of chromospheric (and, therefore, coronal) heating.